BHARATHIDHASANAR
MATRIC HIGHER SECONDARY
SCHOOL, ARAKKONAM-2
STUDY MATERIAL FOR PC
PHYSICS 10 STD
TH
COMPLETED BY
V.SUMATHI, B.SC., B.ED
1
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
S.NO
1.
2
3.
2
UNIT
MEASURING INSTRUMENT
LAWS OF MOTIONS AND
GRAVITATION
ELECTRICITY AND ENERGY
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
UNIT-1: MEASURING INSTRUMENTS
1. To increase Q factor of a coil, the wire should be
A.
long
B.
thin
C.
thick
D.
long and thin
Answer & Explanation
Answer: Option C
Explanation:
Q is high if resistance is low. Therefore, wire should be thick.
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2. An ammeter of 0-25 A range has a guaranteed accuracy of 1% of
full scale reading. The current measured is 5 A. The limiting error
is
A.
2%
B.
2.5%
C.
4%
D.
5%
Answer & Explanation
Answer: Option D
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation:
.
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3. The coil of a moving iron instrument has a resistance of 500 Ω and
an inductance of 1 H. It reads 250 V when a 250 V dc is applied. If
series resistance is 2000 Ω, its reading when fed by 250 V, 50 Hz ac
will be
A.
260 V
B.
252 V
C.
250 V
D.
248 V
Answer & Explanation
Answer: Option D
Explanation:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
4. In 3 phase power measurement by two wattmeter method, the
reading of one wattmeter is zero. The power factor of load is
A.
1
B.
0.5
C.
0
D.
0.8
Answer & Explanation
Answer: Option B
Explanation:
When p.f. = 0.5, 0 = 60° and one of the wattmeters reads zero.
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5. In a CRO which of the following is not a part of electron gun
A.
cathode
B.
grid
C.
accelerating anode
D.
X - Y plates
Answer & Explanation
Answer: Option D
Explanation:
Electron gun consists of cathode, grid and accelerating anode.
6. If reference sound pressure P0 is 2 x 10-5 N/m2, a sound pressure of
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
90 dB is equal to
A.
0.632 N/m2
B.
0.707 N/m2
C.
0.835 N/m2
D.
0.925 N/m2
Answer & Explanation
Answer: Option A
Explanation:
.
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7. Which of the following voltmeters would you use for measuring
voltage across 20 kΩ resistance?
A.
Voltmeter having a resistance of 5 kΩ
B.
Voltmeter having a sensitivity of 1 kW/V
C.
Voltmeter having sensitivity of 10 kW/V
D.
None of the above
Answer & Explanation
Answer: Option C
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation:
Resistance of voltmeter should be very high as compared to 20 kΩ.
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8. A single phase energy meter has the rating 1200 resolutions/ kWh.
If a 500 W electric gadget is used for 4 hours, the energy meter will
make
A.
1200 revolutions
B.
1800 revolutions
C.
2100 revolutions
D.
2400 revolutions
Answer & Explanation
Answer: Option D
Explanation:
0.5 x 4 = 2 kWh = 2 x 1200 revolutions.
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9. Assertion (A): De sauty's bridge is suitable only for pure capacitor.
Reason (R): Capacitors are mostly perfect.
A.
Both A and R are true and R is correct explanation of A
B.
Both A and R are true but R is not correct explanation of A
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
C.
A is true R is false
D.
A is false R is true
Answer & Explanation
Answer: Option C
Explanation:
Capacitors are mostly imperfect.
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10. In which of the transformer is the secondary nearly short circuited
under normal operating conditions?
A.
CT
B.
PT
C.
Distribution transformer
D.
Power transformer
Answer & Explanation
Answer: Option A
Explanation:
CT is operated with secondary short-circuited otherwise a high
emf would be induced across secondary.
11. A moving coil instrument has a resistance of 0.6 Ω and full scale
deflection at 0.1 A. To convert it into an ammeter of 0-15 A range,
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
the resistance of shunt should be
A.
0.6 Ω
B.
0.06 Ω
C.
0.1 Ω
D.
0.004 Ω
Answer & Explanation
Answer: Option D
Explanation:
.
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12. A piezoelectric force transducer has a charge sensitivity of 20
pC/N. It is connected to a charge amplifier and overall gain of
transducer and amplifier is 50 mV/N. The gain of amplifier is
A.
1 mV/pC
B.
1.5 mV/pC
C.
2.5 mV/pC
D.
4 mV/pC
Answer & Explanation
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer: Option C
Explanation:
.
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13. An LVDT is used to measure displacement. The LVDT feeds a
Voltmeter of 0-5 V range through a 250 gain amplifier. For a
displacement 0.5 mm the output of LVDT is 2 mV. The sensitivity
of instrument is
A.
0.1 V/mm
B.
0.5 V/mm
C.
1 V/mm
D.
5 V/mm
Answer & Explanation
Answer: Option C
Explanation:
Final output = 2 x 10-3 x 250 = 0.5 V.
.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
14. Assertion (A): When a wattmeter is used for low impedance loads,
the pressure coil is connected across the load.
Reason (R): A wattmeter measures apparent power.
A.
Both A and R are true and R is correct explanation of A
B.
Both A and R are true but R is not correct explanation of A
C.
A is true R is false
D.
A is false R is true
Answer & Explanation
Answer: Option C
Explanation:
Wattmeter measures active power.
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15. As per BIS there are 6 accuracy classes of instruments.
A.
True
B.
False
Answer & Explanation
Answer: Option B
Explanation:
There are 8 classes of accuracy as per BIS.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
16. In figure, Z1 = 200∠60° Ω, Z2 = 400∠ - 90° Ω, Z3 = 300∠0°. Then
Z4 for bridge to be balanced is
A.
150∠30° Ω
B.
400∠ - 90° Ω
C.
300∠90° Ω
D.
600∠ - 150° Ω
Answer & Explanation
Answer: Option D
Explanation:
.
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17. In a ballistic galvanometer, a charge of 100 μC gives a first swing
of 25°. The charge required to cause first swing of 50° is
A.
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200 μC
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
B.
400 μC
C.
50 μC
D.
25 μC
Answer & Explanation
Answer: Option B
Explanation:
swing is proportional to charge.
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18. Two resistors R1 = 36 Ω ± 5% and R2 = 75 Ω ± 5% are connected in
series. The total resistance is
A.
111 ± 0 Ω
B.
111 ± 2.778 Ω
C.
111 ± 5.55 Ω
D.
111 ± 7.23 Ω
Answer & Explanation
Answer: Option C
Explanation:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Total maximum error ± (1.8 + 3.75) = ± 5.55 Ω.
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19. Figure shows an RC potentiometer to measure ac voltage. It is
desired that V0/Vishould be independent of frequency. The value
of C should be
A.
10 μF
B.
11 μF
C.
0.1 μF
D.
0.09 μF
Answer & Explanation
Answer: Option A
Explanation:
Since resistances are in the ratio of 10 : 1, capacitances should be in
the ratio of 1 : 10 because XC ∝ 1/C.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
20. In a strain measuring device using a strain gauge, the output
quantity is
A.
voltage
B.
resistance
C.
impedance
D.
either (a) or (b)
Answer & Explanation
Answer: Option A
Explanation:
The measurement is done using an unbalanced bridge.
21. The Lissajous pattern observed on screen of CRO is a straight line
inclined at 45° to x axis. If X-plate input is 2 sin ωt, the Y-plate
input is
A.
2 sin ωt
B.
2 sin (ωt + 45°)
C.
2 sin (ωt - 45°)
D.
22 sin ωt + 45°)
Answer & Explanation
Answer: Option A
Explanation:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
When signals to X and Y plates are in phase, the display is a
straight line inclined at 45°.
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22. The angle δ for a mica capacitor is about
A.
25°
B.
15°
C.
5°
D.
1°
Answer & Explanation
Answer: Option D
Explanation:
Mica capacitor has very low loss and loss angle δ is very very
small.
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23. A digital voltmeter has a read out range from 0 to 999 counts. If the
full scale reading is 9.999 V, the resolution is
A.
1V
B.
0.01 V
C.
1 mV
D.
1 μV
Answer & Explanation
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer: Option C
Explanation:
Resolution is the smallest change in the quantity being measured
which will cause an observable change in output. In this case it is 1
mV.
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24. The coil of a moving coil meter has 100 turns, is 40 mm long and 30
mm wide. The control torque is 240 x 10-6 N-m on full scale. If B = 1
Wb/m2, range of meter is
A.
1 mA
B.
2 mA
C.
3 mA
D.
4 mA
Answer & Explanation
Answer: Option B
Explanation:
NBAI = Controlling torque or
= 240 x 10-6 or I = 2 mA.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
25. Consider the following statements: In a differential amplifier using
JFET, the differential output offset is due to
1. mismatch between FET parameters
2. difference in values of resistances used in circuit
3. variation in supply voltage.
Of the statements, the correct statements are
A.
1 and 2
B.
1, 2, 3
C.
2, 3
D.
1, 3
Answer & Explanation
Answer: Option A
Explanation:
Variation in supply voltage affects both amplifiers equally.
26. Magnetic flux density has the dimensions
A.
MI-1T-2
B.
M-1I-2T-2
C.
ML-3T-2
D.
MI-1T-3
Answer & Explanation
Answer: Option A
Explanation:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Flux density = flux/area.
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27. A meter with a resistance of 100 Ω and a full scale deflection of
current of 1 mA is to be converted into voltmeter of 0 - 5 V range.
The multiplier resistance should be
A.
490 Ω
B.
5000 Ω
C.
4900 Ω
D.
5100 Ω
Answer & Explanation
Answer: Option C
Explanation:
.
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28. In a resistance strain gauge, G = 2, stress = 1050 kg/cm2, R = 1000
Ω. The value of ΔR will be
A.
2Ω
B.
3Ω
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
C.
4Ω
D.
1Ω
Answer & Explanation
Answer: Option D
Explanation:
.
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29. The household energy meter is
A.
indicating instrument
B.
recording instrument
C.
integrating instrument
D.
none of the above
Answer & Explanation
Answer: Option C
Explanation:
It integrates energy over a period of time.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
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30. A standard cell of 1.0185 V is used with a slide wire potentiometer.
The balance was obtained at 60 cm. When an unknown emf was
connected, the balance was obtained at 82 cm. The magnitude of
unknown emf is
A.
1.39 V
B.
0.75 V
C.
13.9 V
D.
7.45 V
Answer & Explanation
Answer: Option A
Explanation:
31. A full wave rectifier type meter is used to measure the wave shape
shown in figure. The voltmeter is calibrated to read rms value of
sine wave. The reading of voltmeter will be
A.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
B.
C.
100 V
D.
111 V
Answer & Explanation
Answer: Option D
Explanation:
Peak value of sine wave = 100 x 1.11 = 111 V.
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32. A moving coil instrument has a resistance of 0.5 Ω and a full scale
deflection of 0.1 A. To convert it into an ammeter of 0-10 A the
shunt resistance should be
A.
0.004 Ω
B.
0.005 Ω
C.
0.05 Ω
D.
0.1 Ω
Answer & Explanation
Answer: Option B
Explanation:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
.
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33. Potentiometer method of dc voltage measurement is more accurate
than direct measurement using a voltmeter because
A.
it loads the circuit to maximum extent
B.
it loads the circuit moderately
C.
it does not load the circuit at all
D.
it uses centre zero galvanometer instead of Voltmeters
Answer & Explanation
Answer: Option C
Explanation:
Since the circuit is not loaded, the accurate value of dc voltage is
measured.
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34. Assertion (A): A hot wire ammeter has a cramped scale.
Reason (R): The heat is proportional to square of current.
A.
Both A and R are true and R is correct explanation of A
B.
Both A and R are true but R is not correct explanation of A
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
C.
A is true R is false
D.
A is false R is true
Answer & Explanation
Answer: Option A
Explanation:
Since heating ∝ I2, scale is cramped.
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35. Which of the following is true about an impulse voltage?
A.
It is a unidirectional voltage
B.
Chopped impulse flashover does not occur
C.
Time taken to rise is equal to time taken to fall
D.
RMS value is always less than 50% of average value
Answer & Explanation
Answer: Option A
Explanation:
Impulse is unidirectional (either positive or negative).
36. Which of the following are needed both for protection and
metering?
A.
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Wattmeters
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
B.
Instrument transformers
C.
Energy meters
D.
Power factor meters
Answer & Explanation
Answer: Option B
Explanation:
Instrument transformers are used to measure high currents and
voltages. They also feed the relays for protection.
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37. A digital frequency counter can be converted to DVM by addition
of a suitable
A.
voltage controlled oscillator
B.
D/A converter
C.
power amplifier
D.
operational amplifier
Answer & Explanation
Answer: Option B
Explanation:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
D/A converter changes digital output to analog output.
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38. A dynamometer wattmeter is connected in ac circuit. The reading
will be
A.
V-A product
B.
average power
C.
peak power
D.
instantaneous power
Answer & Explanation
Answer: Option B
Explanation:
Wattmeter measures average power over a cycle.
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39. The speed transducer using a drag cup rotor has the main
advantage of
A.
very high accuracy
B.
low energy requirement
C.
cheap construction
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
D.
all of the above
Answer & Explanation
Answer: Option B
Explanation:
A drag cup rotor has low inertia. Therefore it requires little
amount of energy.
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40. A voltmeter using thermocouples measures
A.
rms value
B.
peak value
C.
average value
D.
peak to peak value
Answer & Explanation
Answer: Option A
Explanation:
Since the thermocouple is based on heating effect, rms value is
measured.
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41. Which of the following measurements using a dc potentiometer do
not require standardisation of potentiometer?
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
A.
Measurement of unknown voltage
B.
Measurement of resistance
C.
Measurement of unknown current
D.
Calibration of voltmeter
Answer & Explanation
Answer: Option B
Explanation:
Unknown resistance is compared with a standard resistance.
Therefore standardisation of potentiometer is not necessary.
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42. Which of the following statement is correct for two wattmeters
method of power measurement in 3 phase circuit?
A.
Power can be measured by this method only for star
connected loads
B.
When two wattmeters have equal readings power factor is
0.5.
C.
When power factor is 1, one of the wattmeters readings is
zero
D.
When the two wattmeter read equal and opposite, p.f. is
zero.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
Answer: Option D
Explanation:
When p.f. is zero, active power is zero and the two redaings are
equal and opposite.
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43. In a thermocouple temperature transducer, the output voltage is
usually measured by
A.
high resistance ammeter
B.
high resistance voltmeter
C.
high resistance milli-voltmeter
D.
none of the above
Answer & Explanation
Answer: Option C
Explanation:
The output voltage is very small. So we need a milli voltmeter.
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44. A moving iron instrument gives correct reading when used at
A.
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low frequencies
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
B.
high frequencies
C.
only one frequency
D.
all frequencies upto a certain value
Answer & Explanation
Answer: Option C
Explanation:
If frequency changes reactance of coil changes and reading is
affected.
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45. Induction wattmeter can be used in
A.
ac circuit only
B.
dc circuit only
C.
both ac and dc circuit
D.
ac 3 phase only
Answer & Explanation
Answer: Option A
Explanation:
Induction effect occurs with ac only.
46. A dynamometer wattmeter is connected in ac circuit. The
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
measured power is
A.
rms power
B.
average power
C.
peak power
D.
instantaneous power
Answer & Explanation
Answer: Option B
Explanation:
All wattmeters measure average power over a cycle.
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47. Loss of charge method is suitable for medium resistances.
A.
True
B.
False
Answer & Explanation
Answer: Option B
Explanation:
It is suitable for high resistances.
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48. In two wattmeter method of 3 phase power measurement, when
does one wattmeter read negative
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
A.
when power factor is less than 0.5 lagging
B.
when power factor is greater than 0.5 lagging
C.
when power factor is less than 0.5
D.
when power factor is unity
Answer & Explanation
Answer: Option C
Explanation:
When p.f. is less than 0.5 (leading or lagging) one of the
wattmeters reads negative.
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49. It is required to measure angular position. Out of the transducers
1.
2.
3.
4.
Circular potentiometer
LVDT
E pick up
Synchro
The proper devices are
A.
1, 2, 3, 4
B.
2 and 3
C.
1, 2, 4
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
D.
1 and 4
Answer & Explanation
Answer: Option D
Explanation:
LVDT and E pickup are suitable for linear displacement.
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50. In figure the bridge is balanced when Z4 is
A.
120∠70°
B.
187.5∠ - 10°
C.
187.5∠ - 70°
D.
333.3∠ - 70°
Answer & Explanation
Answer: Option C
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation:
.
1. What device is similar to an RTD but has a negative temperature
coefficient?
A.
Strain gauge
B.
Thermistor
C.
Negative-type RTD
D.
Thermocouple
Answer & Explanation
Answer: Option B
Explanation:
No answer description available for this question. Let us discuss.
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2. The resistive change of a strain gauge
A.
is based on the weight placed upon it, but can be many
thousands of ohms
B.
is usually no more than 100
C.
is based on the gauge factor, but is typically less than an
ohm
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
D.
has a positive temperature coefficient
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
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3. The silicon-controlled rectifier can be turned off
A.
by a negative gate pulse
B.
by forced commutation
C.
with the off switch
D.
when the breakover voltage is exceeded
Answer & Explanation
Answer: Option B
Explanation:
No answer description available for this question. Let us discuss.
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4. The output voltage of a typical thermocouple is
A.
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less than 100 mV
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
B.
greater than 1 V
C.
Thermocouples vary resistance, not voltage.
D.
None of the above
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
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5. The connections to a thermocouple
A.
can produce an unwanted thermocouple effect, which
must be compensated for
B.
produce an extra desirable thermocouple effect
C.
must be protected, since high voltages are present
D.
produce an extra desirable thermocouple effect and must
be protected, since high voltages are present
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
6. What is the zero-voltage switch used for?
A.
To reduce radiation of high frequencies during turn-on of
a high current to a load
B.
To control low-voltage circuits
C.
To provide power to a circuit when power is lost
D.
For extremely low-voltage applications
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
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7. Temperature sensing can be achieved by the use of
A.
thermocouples
B.
RTDs
C.
thermistors
D.
All of the above
Answer & Explanation
Answer: Option D
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation:
No answer description available for this question. Let us discuss.
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8. The purpose of compensation for a thermocouple is
A.
to decrease temperature sensitivity
B.
to increase voltage output
C.
to cancel unwanted voltage output of a thermocouple
D.
used for high-temperature circuits
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
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9. The change in value of an analog signal during the conversion
process produces what is called the
A.
quantization error
B.
resolution error
C.
Nyquist error
38
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
D.
sampling error
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
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10. Which of the following performance specifications applies to a
sample-and-hold circuit?
A.
Aperture time
B.
Aperture droop
C.
Feedback
D.
Acquisition jitter
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
11. RTDs are typically connected with other fixed resistors
A.
in a pi configuration
B.
in a bridge configuration
39
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
C.
and variable resistors
D.
and capacitors in a filter-type circuit
Answer & Explanation
Answer: Option B
Explanation:
No answer description available for this question. Let us discuss.
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12. Holding current for an SCR is best described as
A.
the minimum current required for turn-off
B.
the current required before an SCR will turn on
C.
the amount of current required to maintain conduction
D.
the gate current required to maintain conduction
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
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13. What is the moving part of a linear variable differential
40
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
transformer?
A.
Primary
B.
Secondary
C.
Diaphragm
D.
Core
Answer & Explanation
Answer: Option D
Explanation:
No answer description available for this question. Let us discuss.
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1. What is the unit for measuring the amplitude of a sound?
A.
Decibel
B.
Coulomb
C.
Hum
D.
Cycles
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
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2. Reading of a barometer going down is an indication of
A.
snow
B.
storm
41
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
C.
intense heat
D.
rainfall
Answer & Explanation
Answer: Option D
Explanation:
No answer description available for this question. Let us discuss.
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3. Decibel is the unit for
A.
speed of light
B.
radio wave frequency
C.
intensity of sound
D.
intensity of heat
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
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4. One fathom is equal to
42
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
A.
6 feet
B.
6 meters
C.
60 feet
D.
100 cm
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
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5. Fathom is the unit of
A.
sound
B.
depth
C.
frequency
D.
distance
Answer & Explanation
Answer: Option B
Explanation:
No answer description available for this question. Let us discuss.
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6. Light year is a measurement of
43
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
A.
speed of aeroplanes
B.
speed of light
C.
Stellar distances
D.
speed of rockets
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
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7. Very small time intervals are accurately measure by
A.
White dwarfs
B.
Quartz clocks
C.
Atomic clocks
D.
Pulsars
Answer & Explanation
Answer: Option C
Explanation:
44
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
No answer description available for this question. Let us discuss.
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8. One kilometre is equal to how many miles?
A.
0.84
B.
0.5
C.
1.6
D.
0.62
Answer & Explanation
Answer: Option D
Explanation:
No answer description available for this question. Let us discuss.
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9. kilohertz is a unit which measures
A.
power used by a current of one ampere
B.
electromagnetic radio wave frequencies
C.
voltage
D.
electric resistance
Answer & Explanation
Answer: Option B
Explanation:
45
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
No answer description available for this question. Let us discuss.
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10. One horse power is equal to
A.
746 watts
B.
748 watts
C.
756 watts
D.
736 watts
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
11. 'Bar' is the unit of
A.
temperature
B.
heat
C.
atmospheric pressure
D.
current
Answer & Explanation
Answer: Option C
46
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation:
No answer description available for this question. Let us discuss.
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12. One Joule is equal to
A.
105 ergs
B.
103 ergs
C.
107 ergs
D.
1011 ergs
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
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13. Kilowatt is a unit to measure
A.
work
B.
power
C.
electricity
D.
current
Answer & Explanation
Answer: Option B
47
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation:
No answer description available for this question. Let us discuss.
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14. Electric current is measure by
A.
commutator
B.
anemometer
C.
ammeter
D.
voltmeter
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
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15. A chronometer measures
A.
colour contrast
B.
sound waves
C.
time
D.
water waves
Answer & Explanation
Answer: Option C
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation:
No answer description available for this question. Let us discuss.
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16. Nautical mile is a unit of distance used in
A.
navigation
B.
road mile
C.
astronomy
D.
measuring the boundaries of a nation
Answer & Explanation
Answer: Option A
Explanation:
No answer description available for this question. Let us discuss.
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17. Knot is a unit of speed of which of the following?
A.
Aeroplane
B.
Light waves
C.
Ship
D.
Sound waves
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
Answer: Option C
Explanation:
No answer description available for this question. Let us discuss.
Unit-2: laws of motions and gravitation
1. The value of ‘g’ at a particular point is 9.8 m/s2 . Suppose the earth suddenly
shrinks uniformly to half its present size without losing any mass. The value of
‘g’ at the same point (assuming that the distance of the point from the centre of
earth does not shrink) will now be . [NCERT 1984; DPM]
4.9 m/s2
9.8 m/s2
3.1 m/s2
19.6 m/s2
Answer & Explanation
9.8 m/s2
Answer:
Explanation: g = (GM/r2). Since M and r are constant, so g=9.8
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2. The radius of the earth is 6400 km and g= 10 In order that a body of 5 kg weig
zero at the equator, the angular speed of the earth is. [MP PMT 1985]
1/80 radian/sec
1/800 radian/sec
1/400 radian/sec
1/1600 radian/sec
Answer & Explanation
1/800 radian/sec
Answer:
Explanation: ω = √(g/R) = √(1/640*1000) = 1/8000
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50
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
3. At what distance from the centre of the earth, the value of acceleration due to
gravity g will be half that on the surface (R = radius of earth). [MP PMT 2001]
2R
1.414 R
R
0.414 R
Answer & Explanation
0.414 R
Answer:
Explanation: Help us to explain question in discussion
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4. Assuming earth to be a sphere of a uniform density, what is the value of
gravitational acceleration in a mine 100 km below the earth’s surface (Given R =
6400 km) . [AFMC 2000; Pb. ]
9.66 m/s2
5.06 m/s2
7.64 m/s2
3.10 m/s2
Answer & Explanation
9.66 m/s2
Answer:
Explanation: g' = g(1-(d/r)) = 9.8(1-(100/6400)) = 9.66
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5. If the distance between two masses is doubled, the gravitational attraction
between them . [AMU (Med.) 2000]
Is doubled
Is reduced to half
Becomes four times
Is reduced to a quarter
Answer & Explanation
Is reduced to a quarter
Answer:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation: F proportional 1/r2 If r becomes double then F reduces to F/4
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6. The mass of the earth is 81 times that of the moon and the radius of the earth
3.5 times that of the moon. The ratio of the acceleration due to gravity at the
surface of the moon to that at the surface of the earth is. [MP PMT 1994]
0.15
1
0.04
6
Answer & Explanation
0.15
Answer:
Explanation: g = GM/R2 (given Me = 81Mm Re = 3.5Rm ) so gm/ge = 0.15
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7. Weightlessness experienced while orbiting the earth in space-ship, is the resu
of. [NCERT 1978; DPM]
Inertia
Zero gravity
Acceleration
Free fall towards earth
Answer & Explanation
Free fall towards earth
Answer:
Explanation: Help us to explain question in discussion
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8. If radius of earth is R then the height ‘h’ at which value of ‘g’ becomes onefourth is . [BHU 2000]
R/4
R
3R/4
R/8
Answer & Explanation
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
R
Answer:
Explanation: g' = g(R/(R+h))2 = g/4 By solving h = R
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9. Reason of weightlessness in a satellite is . [RPMT 2000]
Zero gravity
Zero reaction force by satellite surface
Centre of mass
None
Answer & Explanation
Zero reaction force by satellite surface
Answer:
Explanation: Help us to explain question in discussion
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10. The gravitational force between two point masses m1 and m2 at separation r
given by F = km1m2/r2 The constant k. [CPMT 1993]
Depends on system of units only
Depends on both (a) and (b)
Depends on medium between masses
Is independent of both (a) and
only
(b)
Answer & Explanation
Depends on system of units only
Answer:
Explanation: k represents gravitational constant which depends only on the
system of units
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11. Gravitational mass is proportional to gravitational . [AIIMS 1998]
Field
Intensity
Force
All of these
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
All of these
Answer:
Explanation: Help us to explain question in discussion
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12. At what height over the earth's pole, the free fall acceleration decreases by o
percent (assume the radius of earth to be 6400 km) . [KCET 1994]
32 km
1.253 km
80 km
64 km
Answer & Explanation
32 km
Answer:
Explanation: Help us to explain question in discussion
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13. The tidal waves in the sea are primarily due to
The gravitational effect of the moon
The gravitational effect of venus
on the earth
on the earth
The gravitational effect of the sun
on the earth
The atmospheric effect of the
earth itself
Answer & Explanation
The gravitational effect of the moon on the earth
Answer:
Explanation: Help us to explain question in discussion
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14. The atmosphere is held to the earth by . [IIT 1986]
Winds
Clouds
Gravity
None of the above
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
Gravity
Answer:
Explanation: Help us to explain question in discussion
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15. If density of earth increased 4 times and its radius become half of what it is,
our weight will . [AMU (Engg.) 200]
Be four times its present value
Remain same
Be doubled
Be halved
Answer & Explanation
Be doubled
Answer:
Explanation: Help us to explain question in discussion
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16. Force of gravity is least at. [CPMT 1992]
The equator
A point in between equator and any pole
The poles
None of these
Answer & Explanation
The equator
Answer:
Explanation: Help us to explain question in discussion
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17. If radius of the earth contracts 2% and its mass remains the same, then weigh
of the body at the earth surface . [CPMT 1997; KCET]
Will decrease
Will remain the same
Will increase
None of these
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
Will increase
Answer:
Explanation: g proportional to 1/R2 If radius of earth decreases by 2% then g
will increase by 4% i.e. weight of the body at earth surface will
increase by 4%
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18. The time period of a simple pendulum on a freely moving artificial satellite
. [CPMT 1984; AFMC]
Zero
3 sec
2 sec
Infinite
Answer & Explanation
Infinite
Answer:
Explanation: Time period of simple pendulum T = 2π√(l/g')
In artificial satellite g' = 0 so T = infinite.
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19. At what height from the ground will the value of ‘g’ be the same as that in 10
km deep mine below the surface of earth . [RPET 1999]
20 km
15 km
10 km
5 km
Answer & Explanation
20 km
Answer:
Explanation: Same change in the value of g can be observed at a depth x and
height 2x given d=x=10km h = 2x = 20km
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20. Which of the following is the evidence to show that there must be a force
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
acting on earth and directed towards the sun . [AIIMS 1980]
Deviation of the falling bodies
towards east
Revolution of the earth round the
sun
Phenomenon of day and night
Apparent motion of sun round
the earth
Answer & Explanation
Revolution of the earth round the sun
Answer:
Explanation: Help us to explain question in discussion
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21. The weight of a body at the centre of the earth is . [AFMC 1988]
Zero
Same as on the surface of earth
Infinite
None of the above
Answer & Explanation
Zero
Answer:
Explanation: Help us to explain question in discussion
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22. Two identical solid copper spheres of radius R placed in contact with each
other. The gravitational attracton between them is proportional to . [Kerala PET
2005]
R2
R4
R-2
R-4
Answer & Explanation
R4
Answer:
Explanation: Help us to explain question in discussion
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
23. Two sphere of mass m and M are situated in air and the gravitational force
between them is F. The space around the masses is now filled with a liquid of
specific gravity 3. The gravitational force will now be . [CBSE PMT 2003]
F
F/9
F/3
3F
Answer & Explanation
F
Answer:
Explanation: Gravitational force does not depend on the medium
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24. If the angular speed of the earth is doubled, the value of acceleration due to
gravity (g) at the north pole .[EAMCET (Med.) 1]
Doubles
Remains same
Becomes half
Becomes zero
Answer & Explanation
Remains same
Answer:
Explanation: Acceleration due to gravity at poles is independent of the
angular speed of earth
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25. Choose the correct statement from the following : Weightlessness of an
astronaut moving in a satellite is a situation of. [MP PMT 1995]
Zero g
Zero mass
No gravity
Free fall
Answer & Explanation
Zero g
Answer:
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Explanation: Help us to explain question in discussion
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26. If mass of a body is M on the earth surface, then the mass of the same body o
the moon surface is . [AIIMS 1997; RPM]
M/6
M
Zero
None of these
Answer & Explanation
M
Answer:
Explanation: Mass does not vary from place to place
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27. The centripetal force acting on a satellite orbiting round the earth and the
gravitational force of earth acting on the satellite both equal F. The net force on
the satellite is. [AMU 1999]
Zero
F√2
F
2F
Answer & Explanation
F
Answer:
Explanation: Help us to explain question in discussion
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28. If the change in the value of ‘g’ at a height h above the surface of the earth is
the same as at a depth x below it, then (both x and h being much smaller than th
radius of the earth) . [NCERT 1983; BHU]
x=h
x = h/2
x = 2h
x = h2
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
x = 2h
Answer:
Explanation: The value of g at the height h from the surface of earth g' = g(1(2h/R))
The value of g at depth x below the surface of earth g' = g(1(x/R))
These two are given equal, hence (1- (2h/R)) = (1- (x/R))
On solving, we get x =2h
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29. The diameters of two planets are in the ratio 4 : 1 and their mean densities in
the ratio 1 : 2. The acceleration due to gravity on the planets will be in ratio. [ISM
Dhanbad 199]
1:2
2:1
2:3
4:1
Answer & Explanation
2:1
Answer:
Explanation: Help us to explain question in discussion
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30. A satellite of the earth is revolving in a circular orbit with a uniform speed v
If the gravitational force suddenly disappears, the satellite will . [AIIMS 1982;
AIE]
Continue to move with velocity v
along the original orbit
Move with a velocity v,
tangentially to the original orbit
Fall down with increasing velocity
Ultimately come to rest
somewhere on the original orbit
Answer & Explanation
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Move with a velocity v, tangentially to the original orbit
Answer:
Explanation: Due to inertia of direction.
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Electricity and energy
1. The number of dry cells, each of emf 1.5 volt and internal resistance 0.5
ohm that must be joined in series with a resistance of 20 ohm so as to send
a current of 0.6 ampere through the circuit is
2
10
8
12
Answer & Explanation
10
Answer:
Explanation: Help us to explain question in discussion
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2. If six identical cells each having an emf of 6 V are connected in parallel,
the emf of the combination is
1V
1/6 V
36V
6V
Answer & Explanation
6V
Answer:
Explanation: Help us to explain question in discussion
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3. The lead wires should have
Larger diameter and low resistance
61
Smaller diameter and low
resistance
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Smaller diameter and high
resistance
Larger diameter and high
resistance
Answer & Explanation
Larger diameter and low resistance
Answer:
Explanation: Help us to explain question in discussion
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4. If the current through 3 n resistor is 0.8 A then the potential drop through
4 Ω resistor is.
9.6 V
2.6 V
4.8 V
2.2 V
Answer & Explanation
4.8 V
Answer:
Explanation: Help us to explain question in discussion
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5. A uniform wire of resistance R is uniformly compressed along its length,
until its radius becomes n times the original radius. New resistance of the
wire becomes
R/n⁴
R/n
R/n²
nR
Answer & Explanation
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer:
R/n⁴
Explanation: Help us to explain question in discussion
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6. An ammeter reads upto 1 ampere. Its internal resistance is 0.81 ohm. To
increase the range to 10 A the value of the required shunt is
0.09 Ω
0.3 Ω
0.03 Ω
0.9 Ω
Answer & Explanation
0.09 Ω
Answer:
Explanation: Help us to explain question in discussion
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7. Two wires A and B of same material and same mass have radius 2 r and r.
If resistance of wire A is 34 Ω, then resistance of B will be
544 Ω
68 Ω
272 Ω
17 Ω
Answer & Explanation
544 Ω
Answer:
Explanation: Help us to explain question in discussion
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8. A wire of 50 cm long and 1 mm² in cross-sectional area carries a current
4A when connected to a 2V battery. The resistivity of the wire is
2 x 10 -7 Ωm
4 x 10 -6 Ωm
5 x 10 -7 Ωm
1 x 10 -6 Ωm
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
1 x 10 -6 Ωm
Answer:
Explanation: Help us to explain question in discussion
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9. The resistance of a wire is R. If the length of the wire is doubled by
stretching, then the new resistance will be
2R
R
4R
R/4
Answer & Explanation
4R
Answer:
Explanation: Help us to explain question in discussion
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10. The resistance of 20 em long wire is 5 ohm. The wir~ is stretched to a
uniform wire of 40 em length. The resistance now will be (in ohms)
5
20
10
200
Answer & Explanation
20
Answer:
Explanation: Help us to explain question in discussion
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1. The number of dry cells, each of emf 1.5 volt and internal resistance 0.5 ohm
that must be joined in series with a resistance of 20 ohm so as to send a current
of 0.6 ampere through the circuit is
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
2
10
8
12
Answer & Explanation
10
Answer:
Explanation: Help us to explain question in discussion
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2. If six identical cells each having an emf of 6 V are connected in parallel, the
emf of the combination is
1V
1/6 V
36V
6V
Answer & Explanation
6V
Answer:
Explanation: Help us to explain question in discussion
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3. The lead wires should have
Larger diameter and low resistance
Smaller diameter and high
resistance
Smaller diameter and low
resistance
Larger diameter and high
resistance
Answer & Explanation
Larger diameter and low resistance
Answer:
Explanation: Help us to explain question in discussion
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65
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
4. If the current through 3 n resistor is 0.8 A then the potential drop through 4 Ω
resistor is.
9.6 V
2.6 V
4.8 V
2.2 V
Answer & Explanation
4.8 V
Answer:
Explanation: Help us to explain question in discussion
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5. A uniform wire of resistance R is uniformly compressed along its length, unt
its radius becomes n times the original radius. New resistance of the wire
becomes
R/n⁴
R/n
R/n²
nR
Answer & Explanation
Answer:
R/n⁴
Explanation: Help us to explain question in discussion
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11. When a piece of aluminium wire finite length is drawn through a series
of dies to reduce its diameter to half its original value, its resistance will
become
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
2 times
8 times
4 times
16 times
Answer & Explanation
16 times
Answer:
Explanation: Help us to explain question in discussion
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12. There are three voltmeters of the same range but of resistances 10000 Ω,
8000 Ω and 4000 Ω respectively. The best voltmeter among these is the one
whose resistance is
10000 Ω
40000 Ω
80000 Ω
None of these
Answer & Explanation
10000 Ω
Answer:
Explanation: Help us to explain question in discussion
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13. A cell of internal resistance 3 ohm and emf 1 volt is connected to a
uniform wire of length 500 em and resistance 3 ohm. The potential gradient
in the wire is
30 mV/cm
20 mV/cm
1 mV/cm
4 mV/cm
Answer & Explanation
1 mV/cm
Answer:
Explanation: Help us to explain question in discussion
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
View Answer
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14. Read the following statements carefully Y: The resistivity of a
semiconductor decreases with increase of temperature Z : In a conducting
solid, rate of collisions between free electrons and ions increases with
increases of temperature Select the correct statements (s) from the
following
Y is true but Z is false
Both Y and Z are true
Y is false but Z is true
Y is true and Z is the correct reason for Y
Answer & Explanation
Both Y and Z are true
Answer:
Explanation: Help us to explain question in discussion
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15. Which of the following does not obey Ohm's law
Copper
Diode-valve
Aluminium
None of these
Answer & Explanation
Diode-valve
Answer:
Explanation: Help us to explain question in discussion
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16. If a wire of resistance R is melted and recasted to half of its length, then
the new resistance of the wire will be. [KCET (Med.) 200]
R/4
R
R/2
2R
68
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
R/4
Answer:
Explanation: Help us to explain question in discussion
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17. In a typical Wheatstone network the resistances in cyclic order are A =
10 Ω, B = 10 Ω, C = 4 nand D = 4 Ω. For the bridge to be
balanced.
10 Ω should be connected in
parallel with A
5 Ω should be connected in series
with B
10 Ω should be connected in series
5 Ω should be connected in
with A
parallel with B
Answer & Explanation
10 Ω should be connected in parallel with A
Answer:
Explanation: Help us to explain question in discussion
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18. Six identical cells of emf E and internal resistance r are connected in
parallel, then the net emf and internal resistance of the combination will be
6E: 6r
E,6r
E,r/6
E/6,r/6
69
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
E,r/6
Answer:
Explanation: Help us to explain question in discussion
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19. In the following figure current flowing through BD. is
.
0
0.066 A
0.033 A
None of these
Answer & Explanation
0
Answer:
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20. Resistances of 6 ohm each are connected in the manner shown in
adjoining figure. With the current ampere as shown in figure, the potential
difference VP - VQ is .
3.6 V
3.0 v
6.0 v
7.2 v
70
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
3.0 v
Answer:
Explanation: Help us to explain question in discussion
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21. An unknown resistance R1 is connected in series with a resistance of
10Ω. This combination is connected to one gap of a metre bridge while a
resistance R2 is connected in the other gap. The balance point is at 50 em.
Now, when the 10 Ω resistance is removed the balance position shifts to 40
em. The value of R1 is (in ohm)
10
40
20
60
Answer & Explanation
20
Answer:
Explanation: Help us to explain question in discussion
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22. The internal resistance of a cell of emf 12 V is 5 x 10 -2 Ω . It is connected
across an unknown resistance. Voltage across the cell, when a current of 60
A is drawn from it, is
15 V
9V
12 V
6V
Answer & Explanation
9V
Answer:
Explanation: Help us to explain question in discussion
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71
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
23. Identify the set in which all the three materials are good conductor of
electricity
Cu, Ag, Au
Cu, Hg, NaCI
Cu, Si, Diamond
Cu, Ge, Hg
Answer & Explanation
Cu, Ag, Au
Answer:
Explanation: Help us to explain question in discussion
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24. If in the circuit shown, the internal resistance of the battery is 1.5 Ω and
VP and VQ are the potentials at P & Q respectively what is the potential
difference between P and Q .
Zero
4 volts (VQ > VP)
4 volts (VP > VQ)
2.5 volts (VQ > VP)
Answer & Explanation
2.5 volts (VQ > VP)
Answer:
Explanation: Help us to explain question in discussion
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25. In the given figure, when galvanometer shows no deflection, the current
72
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
(in ampere) flowing through 5Ω resistance will be.
0.5
0.9
0.6
1.5
Answer & Explanation
0.5
Answer:
Explanation: Help us to explain question in discussion
Unit-3: laws of motions and gravitation
1. A 30 gm bullet initially travelling at 120 m/s penetrates 12 cm into a
wooden block. The average resistance exerted by the wooden block
is. [AFMC 1999; CPMT]
2850N
2000N
2200 N
1800 N
Answer & Explanation
1800 N
Answer:
Explanation: Help us to explain question in discussion
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2. A parachutist of weight ‘w’ strikes the ground with his legs fixed and
comes to rest with an upward acceleration of magnitude 3 g. Force exerted
on him by ground during landing is. [EAMCET 1988]
73
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
w
3w
2w
4w
Answer & Explanation
4w
Answer:
Explanation: Resultant force is w +3w = 4w
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3. A force of 10 Newton acts on a body of mass 20kg for 10 seconds. Chang
in its momentum is. [MP PET 2002]
5 kg m/s
200 kg m/s
100kg m/s
1000kg m/s
Answer & Explanation
100kg m/s
Answer:
Explanation: dp = F * dt = 10*10 = 100 kg m/s
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4. A particle is moving with a constant speed along a straight line path. A
force is not required to. [AFMC 2001]
Increase its speed
Change the direction
Decrease the momentum
Keep it moving with uniform velocity
Answer & Explanation
Keep it moving with uniform velocity
Answer:
Explanation: Particle will move with uniform velocity due to inertia.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
5. A rocket of mass 1000 kg exhausts gases at a rate of 4 kg/sec with a
velocity 3000 m/s. The thrust developed on the rocket is. [Orissa JEE 2005]
12000 N
800 N
120 N
200 N
Answer & Explanation
12000 N
Answer:
Explanation: Help us to explain question in discussion
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6. A lift is moving down with acceleration a. A man in the lift drops a ball
inside the lift. The acceleration of the ball as observed by the man in the
lift and a man standing stationary on the ground are respectively. [AIEEE
2002]
g,g
g-a, g
g-a, g-a
a,g
Answer & Explanation
g-a, g
Answer:
Explanation: Due to relative motion, acceleration of ball observed by
observer in lift = (g – a) and for man on earth the acceleration
remains g.
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7. A body of mass 1.0kg is falling with an acceleration of 10 m/sec2 . Its
apparent weight will be (g = 10) . [MP PET 2002]
75
1.0 kgwt
0.5 kgwt
2.0 kgwt
Zero
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
Zero
Answer:
Explanation: R = m(g-a) = m(10-10) = 0
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8. If force on a rocket having exhaust velocity of 300 m/sec is 210 N, then
rate of combustion of the fuel is . [CBSE PMT 1999; ]
0.7 kg/s
0.07 kg/s
1.4 kg/s
10.7 kg/s
Answer & Explanation
0.7 kg/s
Answer:
Explanation: Help us to explain question in discussion
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9. A man of weight 75 kg is standing in an elevator which is moving with
an acceleration of 5 m/s in upward direction the apparent weight of the
man will be (g=10) . [Pb. PMT 2004]
1425 N
1250 N
1375 N
1125 N
Answer & Explanation
1125 N
Answer:
Explanation: The apparent weight,
R = m(g+a) = 75(10+5) = 1125N
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10. A light spring balance hangs from the hook of the other light spring
balance and a block of mass M kg hangs from the former one. Then the
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
true statement about the scale reading is . [AIEEE 2003]
Both the scales read
The scale of the lower one reads M kg and of the
M/2 kg each
upper one zero
Both the scales read
The reading of the two scales can be anything but
M kg each
the sum of the reading will be M kg
Answer & Explanation
Both the scales read M kg each
Answer:
Explanation: As the spring balance are massless therefore both the scales
read M kg each.
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11. A man weighing 80 kg is standing in a trolley weighing 320 kg. The
trolley is resting on frictionless horizontal rails. If the man starts walking
on the trolley with a speed of 1 m / s, then after 4 sec his displacement
relative to the ground will be. [CPMT 1988, 89, ]
5m
3.2 m
4.8 m
3.0 m
Answer & Explanation
3.2 m
Answer:
Explanation: Help us to explain question in discussion
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12. In which of the following cases forces may not be required to keep
the. [AIIMS 1983]
Particle going in a circle
Particle going along a straight
77
The momentum of the particle
constant
Acceleration of the particle constant
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
line
Answer & Explanation
Acceleration of the particle constant
Answer:
Explanation: If momentum remains constant then force will be zero because
F = dP/dt
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13. An object will continue moving uniformly until . [CPMT 1975]
The resultant force acting on it
begins to decrease
The resultant force on it is zero
The resultant force is at right angle
to its rotation
The resultant force on it is increased
continuously
Answer & Explanation
The resultant force on it is zero
Answer:
Explanation: Help us to explain question in discussion
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14. A person sitting in an open car moving at constant velocity throws a bal
vertically up into air. The ball falls .[EAMCET (Med.) 1]
Outside the car
In the car to the side of the person
In the car ahead of the person
Exactly in the hand which threw it up
Answer & Explanation
Exactly in the hand which threw it up
Answer:
Explanation: Horizontal velocity of ball and person are same so both will
cover equal horizontal distance in a given interval of time and
after following the parabolic path the ball falls exactly in the
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
hand which threw it up.
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15. The average resisting force that must act on a 5 kg mass to reduce its
speed from 65 cm/s to 15 cm/s in 0.2s is . [RPET 2000]
12.5 N
50 N
25 N
100 N
Answer & Explanation
12.5 N
Answer:
Explanation: Help us to explain question in discussion
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16. A block of mass 5kg is moving horizontally at a speed of 1.5 m/s. A
perpendicular force of 5N acts on it for 4 sec. What will be the distance of
the block from the point where the force started acting. [Pb. PMT 2002]
10 m
6m
8m
2m
Answer & Explanation
10 m
Answer:
Explanation: Help us to explain question in discussion
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17. A rope of length 5m is kept on frictionless surface and a force of 5N is
applied to one of its end. Find tension in the rope at 1m from this
end. [RPET 2000]
79
1N
4N
3N
5N
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
4N
Answer:
Explanation: Help us to explain question in discussion
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18. A man is standing on a weighing machine placed in a lift. When
stationary his weight is recorded as 40 kg. If the lift is accelerated upwards
with an acceleration of 2m/s2, then the weight recorded in the machine will
be .[MP PMT 1994]
32 kg
42 kg
40 kg
48 kg
Answer & Explanation
48 kg
Answer:
Explanation: In stationary lift man weighs 40 kg i.e. 400 N.
When lift accelerates upward it's apparent weight = m(g+a) =
40(10+2) = 480N i.e. 48 kg
For the clarity of concepts in this problem kg-wt can be used in
place of kg.
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19. A second's pendulum is mounted in a rocket. Its period of oscillation
decreases when the rocket. [CBSE PMT 1994]
Comes down with uniform
acceleration
Moves up with a uniform
velocity
Moves round the earth in a
geostationary orbit
Moves up with uniform
acceleration
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
Moves up with uniform acceleration
Answer:
Explanation: T = 2π√l/g
T will decrease, If g increases.It is possible when rocket moves
up with uniform acceleration.
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20. A bird weighs 2 kg and is inside a closed cage of 1 kg. If it starts flying,
then what is the weight of the bird and cage assembly. [AFMC 1997]
1.5 kg
3 kg
2.5 kg
4 kg
Answer & Explanation
3 kg
Answer:
Explanation: When the bird flies, it pushes air down to balance its weight. So
the weight of the bird and closed cage assembly remains
unchanged.
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21. If a bullet of mass 5 gm moving with velocity 100 m /sec, penetrates the
wooden block upto 6 cm. Then the average force imposed by the bullet on
the block is . [MP PMT 2003]
8300 N
830 N
417 N
Zero
Answer & Explanation
417 N
Answer:
Explanation: Help us to explain question in discussion
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
22. A man is at rest in the middle of a pond on perfectly smooth ice. He can
get himself to the shore by making use of Newton's. [CPMT 1981]
First law
Third law
Second law
All the laws
Answer & Explanation
Third law
Answer:
Explanation: Help us to explain question in discussion
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23. A wagon weighing 1000 kg is moving with a velocity 50km/h on smooth
horizontal rails. A mass of 250 kg is dropped into it. The velocity with
which it moves now is . [MP PMT 1994]
2.5 km/hour
40 km/hour
20 km/hour
50 km/hour
Answer & Explanation
40 km/hour
Answer:
Explanation: According to principle of conservation of linear momentum
1000*50 = 1250 * v so v = 40km/hr
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24. A man is standing at the centre of frictionless pond of ice. How can he
get himself to the shore . [J&K CET 2005]
By throwing his shirt in vertically
upward direction
By spitting horizontally
He will wait for the ice to
melt in pond
Unable to get at the shore
Answer & Explanation
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
By spitting horizontally
Answer:
Explanation: Help us to explain question in discussion
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25. Newton's third law of motion leads to the law of conservation
of. [Manipal MEE 199]
Angular momentum
Mass
Energy
Momentum
Answer & Explanation
Momentum
Answer:
Explanation: Help us to explain question in discussion
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26. When a bus suddenly takes a turn, the passengers are thrown outwards
because of . [AFMC 1999; CPMT]
Inertia of motion
Speed of motion
Acceleration of motion
Both (b) and (c)
Answer & Explanation
Inertia of motion
Answer:
Explanation: Help us to explain question in discussion
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27. A spring balance is attached to the ceiling of a lift. A man hangs his bag
on the spring and the spring reads 49 N, when the lift is stationary. If the
lift moves downward with an acceleration of 5m/s2 the reading of the
spring balance will be . [AIEEE 2003]
49 N
83
74 N
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
24 N
15 N
Answer & Explanation
24 N
Answer:
Explanation: When the lift is stationary W = mg = 49 = m*9.8 so m = 5kg
When the lift is moving downward with an acceleration R =
m(9.8-a) = 5[9.8-5] = 24N
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28. A cricket ball of mass 250 g collides with a bat with velocity 10 m/s and
returns with the same velocity within 0.01 second. The force acted on bat
is. [CPMT 1997]
25 N
250 N
50 N
500 N
Answer & Explanation
500 N
Answer:
Explanation: Force = m(dv/dt)
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29. A body, whose momentum is constant, must have constant . [AIIMS
2000]
Force
Acceleration
Velocity
All of these
Answer & Explanation
Velocity
Answer:
Explanation: For a given mass P propotinal to v . If the momentum is
constant then it's velocity must have constant
84
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
View Answer
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30. Gravels are dropped on a conveyor belt at the rate of 0.5 kg/sec. The
extra force required in newtons to keep the belt moving at 2 m/sec
is. [EAMCET 1988]
1
4
2
0.5
Answer & Explanation
1
Answer:
Explanation: F = u(dm/dt) = 2*0.5 = 1N same amount of force is required to
keep the belt moving at 2 m/s
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31. An automobile travelling with a speed of 60km/h can brake to stop
within a distance of 20 m. If the car is going twice as fast, i.e. 120 km/h, the
stopping distance will be . [AIEEE 2004]
20 m
60 m
40 m
80 m
Answer & Explanation
80 m
Answer:
Explanation: Help us to explain question in discussion
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32. If a person with a spring balance and a body hanging from it goes up
and up in an aeroplane, then the reading of the weight of the body as
indicated by the spring balance will . [AIIMS 1998; JIP]
Go on increasing
85
First increase and then decrease
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Go on decreasing
Remain the same
Answer & Explanation
First increase and then decrease
Answer:
Explanation: Initially due to upward acceleration apparent weight of the
body increases but then it decreases due to decrease in gravity.
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33. In the above problem, if the lift moves up with a constant velocity of 2
m/sec, the reading on the balance will be . [NCERT 1977]
2 kg
Zero
4 kg
1 kg
Answer & Explanation
2 kg
Answer:
Explanation: The lift is not accelerated, hence the reading of the balance will
be equal to the true weight. R=mg=2gNewton or 2kg
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34. A mass of 1 kg is suspended by a string A. Another string C is
connected to its lower end (see figure). If a sudden jerk is given to C, then
The portion AB of the string will break
None of the strings will break
The portion BC of the string will break
The mass will start rotating
Answer & Explanation
The portion BC of the string will break
Answer:
Explanation: When a sudden jerk is given to C, an impulsive tension
exceeding the breaking tension develops in C first, which
breaks before this impulse can reach A as a wave through
86
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
block.
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35. In doubling the mass and acceleration of the mass, the force acting on
the mass with respect to the previous value
Decreases to half
Increases two times
Remains unchanged
Increases four times
Answer & Explanation
Increases four times
Answer:
Explanation: Force = Mass x Acceleration. If mass and acceleration both are
doubled then force will become four times.
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36. A lift of mass 1000 kg is moving with an acceleration of 1 m/s2 in
upward direction. Tension developed in the string, which is connected to
the lift, is. [CBSE PMT 2002]
9,800 N
10,800 N
10,000 N
11,000 N
Answer & Explanation
10,800 N
Answer:
Explanation: T = m(g+a) = 1000(9.8+1) = 10800N
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37. A student attempts to pull himself up by tugging on his hair. He will
not succeed. [KCET 2005]
As the force exerted is small
87
Newton's law of inertia is not
applicable to living beings.
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
The frictional force while
gripping, is small.
As the force applied is internal to the
system.
Answer & Explanation
As the force applied is internal to the system.
Answer:
Explanation: As by an internal force momentum of the system can not be
changed.
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38. A force of 100 dynes acts on mass of 5 gm for 10 sec. The velocity
produced is. [MNR 1987]
2 cm/sec
200 cm/sec
20 cm/sec
2000 cm/sec
Answer & Explanation
200 cm/sec
Answer:
Explanation: Acceleration a = F/m = 100/5 = 20 cm/s2
Now v = at = 20*10 = 200cm/s
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39. A jet engine works on the principle of . [CPMT 1973; MP P]
Conservation of mass
Conservation of linear momentum
Conservation of energy
Conservation of angular momentum
Answer & Explanation
Conservation of linear momentum
Answer:
Explanation: Help us to explain question in discussion
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
40. A body of mass 2 kg is hung on a spring balance mounted vertically in a
lift. If the lift descends with an acceleration equal to the acceleration due to
gravity ‘g’, the reading on the spring balance will be . [NCERT 1977]
2 kg
(2*g)kg
(4*g)kg
Zero
Answer & Explanation
Zero
Answer:
Explanation: Reading on the spring balance = m (g – a)
and since a = g hence Force = 0
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41. A body of mass 2 kg moving on a horizontal surface with an initial
velocity of 4 m/sec comes to rest after 2 sec. If one wants to keep this body
moving on the same surface with a velocity of 4 m/sec, the force required
is.[NCERT 1977]
8N
Zero
4N
2N
Answer & Explanation
4N
Answer:
Explanation: Help us to explain question in discussion
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42. A cork is submerged in water by a spring attached to the bottom of a
pail. When the pail is kept in a elevator moving with an acceleration
downwards, the spring length . [EAMCET (Engg.) ]
Increases
Remains unchanged
Decreases
Data insufficient
89
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
Decreases
Answer:
Explanation: Density of cork = d, Density of water = ρ Resultant upward
force on cork = V(ρ-d)g This causes elongation in the spring.
When the lift moves down with acceleration a, the resultant
upward force on cork = V(ρ-d)(g-a) which is less than the
previous value. So the elongation decreases.
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43. A diwali rocket is ejecting 0.05 kg of gases per second at a velocity of
400 m/sec. The accelerating force on the rocket is. [NCERT 1979; DPM]
20 dynes
22 dynes
20 N
1000 N
Answer & Explanation
20 N
Answer:
Explanation: F = u(dm/dt) = 400*0.05 = 20N
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44. Rocket engines lift a rocket from the earth surface because hot gas with
high velocity. [AIIMS 1998; JIP]
Push against the earth
React against the rocket and push it up
Push against the air
Heat up the air which lifts the rocket
Answer & Explanation
React against the rocket and push it up
Answer:
Explanation: It works on the principle of conservation of momentum.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
45. A cold soft drink is kept on the balance. When the cap is open, then the
weight. [AFMC 1996]
Increases
First increases then decreases
Decreases
Remains same
Answer & Explanation
First increases then decreases
Answer:
Explanation: Gas will come out with sufficient speed in forward direction, so
reaction of this forward force will change the reading of the
spring balance
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46. A force of 5 N acts on a body of weight 9.8 N. What is the acceleration
produced in m/sec2. [NCERT 1990]
49.00
1.46
5.00
0.51
Answer & Explanation
5.00
Answer:
Explanation: As weight = 9.8 N Mass = 1 kg
Acceleration = Force/Mass = 5/1 = 5m/s2
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47. Swimming is possible on account of . [AFMC 1998, 2003]
First law of motion
Third law of motion
Second law of motion
Newton's law of gravitation
Answer & Explanation
91
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Third law of motion
Answer:
Explanation: Swimming is a result of pushing water in the opposite
direction of the motion.
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48. Newton's first law of motion describes the following . [MP PMT 1996]
Energy
Inertia
Work
Moment of inertia
Answer & Explanation
Inertia
Answer:
Explanation: Newton’s first law of motion defines the inertia of body. It
states that every body has a tendency to remain in its state
(either rest or motion) due to its inerta.
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49. Newton's second law gives the measure of . [CPMT 1982]
Acceleration
Momentum
Force
Angular momentum
Answer & Explanation
Force
Answer:
Explanation: F = ma
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50. In the above Question, if the string C is stretched slowly, then
The portion AB of the string will break
None of the strings will break
The portion BC of the string will break
None of the above
92
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Answer & Explanation
The portion AB of the string will break
Answer:
Explanation: When the spring C is stretched slowly, the tension in A is
greater than that of C, because of the weight mg and the
former reaches breaking point earlier.
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BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics
Thanking you
94
BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM _ 10th PC Physics