Digital Assignment II
Answer only to the question corresponding to your register number
in a Neat A4 size paper, after writing your name and registration
number along with the question.
REGISTER NO
NAME
18BEE0320
19BEE0004
19BEE0086
19BEE0097
19BEE0155
19BEE0213
19BEE0300
19BEE0346
19BEE0362
19BEE0406
19BEE0414
20BEE0001
20BEE0009
20BEE0011
20BEE0014
20BEE0016
20BEE0037
20BEE0052
20BEE0054
20BEE0056
20BEE0067
20BEE0075
20BEE0081
20BEE0085
20BEE0094
20BEE0104
20BEE0105
20BEE0107
20BEE0127
20BEE0139
20BEE0145
20BEE0150
20BEE0172
20BEE0176
RIJU MALLICK
SHIVAM RAJPUT
HARSH PANDEY
ARSHIT YADAV
NILAY MISHRA
C VIHITHA REDDY
PANTRA DHAMINI RAO
ISHAN MAHAJAN
ADWAIT GIRISH MAHAJAN
MANICKAM S
MANOJKUMAR M
SIDDHARTH S
MAHESH NAMBOODIRI
MONISHKUMAR P
SRINIVASAN R
DIPTANSHU DE
VIJENDRA SINGH
HARI HARAN G
ARHAM DODAL
SANCHIT AGARWAL
PRIYANSHU KUMAR
RISHVANTH SK
WINSTON ARFIN V
GAUTAM KARTHIK V
AKHIL KODALAPURAM
MAYANK SHAH P
ARKA DEY
VISHAL GARG
SHUBHAM SHARMA
RAJVEER M
JOHN JOSE KORATH
SUBASH S
YASH SHARMA
VIDHYA SAKAR
Q. NO
9
33
26
31
5
45
18
36
29
55
60
41
39
49
25
37
3
6
21
34
64
58
8
16
7
62
65
4
2
30
28
48
23
61
REGISTER NO
20BEE0181
20BEE0185
20BEE0191
20BEE0199
20BEE0209
20BEE0214
20BEE0224
20BEE0225
20BEE0229
20BEE0232
20BEE0233
20BEE0234
20BEE0238
20BEE0243
20BEE0252
20BEE0261
20BEE0268
20BEE0271
20BEE0278
20BEE0320
20BEE0321
20BEE0322
20BEE0323
20BEE0324
20BEE0336
20BEE0344
20BEE0346
20BEE0351
20BEE0354
20BEE0356
20BEI0031
Name
RITHICK SARATHI M B
PRATHAM SUDHIR
DEVANSHU SHARMA
SAURABH VIJAY MUNJAL
ADITYA RAJ
RAJ DIGAMBAR FALKE
SURENDRA AGRAWAL
NABEEL MOHAMMED
VIKAS
SHARDUL DEEPAK
RAVINUTHALA
MOHAMMAD MUAZZAM
JEEVAA SR
MATHIVANNAN S
NITHIN K
AMIT KUMAR GUPTA
SIDDARTH S
PIYUSH CHAURASIA
ANUJ MATHUR
SHANMUGARAJ P
SAKTHIVEL A
VANITHA P
JAGANATHAN R
RAMAMOORTHI S
DAXAY SOJITRA
ANUSHA Y
MILIND CHATURVEDI
HARSHIT SAH
SUMIT DUTTA
NADAGOUDA ABHISHEK
SUNDER M
Q.No
46
24
17
32
20
38
43
1
27
11
22
54
52
42
14
47
13
35
50
56
40
53
10
15
51
63
44
57
19
12
59
1.
A 200V 10A dynamometer type wattmeter has resistance of current and pressure coils as 0.8Ω
and 10,000Ω respectively. Determine the percentage errors due to resistance for each of the two
methods of connections when 0.75 power factor lagging loads at 200V, and current 1) 1A and (2) 8A is
applied. Neglect errors due to inductance of pressure circuit.
2.
The measurement of resistance of a resistor gives the following results 101.2, 101.7, 101.3,
101.0, 101.5, 101.3, 101.2, 101.4, 101.3 and 101.1 ohms. Assuming the random errors are present
calculate (i) arithmetic mean, (ii) the standard deviation of the reading (iii) the probable error of average
of 10 readings.
3.
Following readings were obtained in respect of measurement of resistor. 0.903, 0.895, 0.892,
0.899, 0.901, 0.890, 0.906, 0.897, 0.912, 0.892, 0.898, 0.902. Determine (a) the arithmetic mean, (b)
standard deviation of the readings (c) the probable error of mean value
4.
A 250V moving iron voltmeter has coil resistance of 500 ohms coil inductance of 1.04 and a
series resistance of 2kiloohms. The meter reads correctly at 250V dc. What will be the value of
capacitance to be used for shunting the series resistance to make the meter read correctly at 50Hz.
5.
The inductance of a certain moving iron ammeter is (8 + 4 - ½ 2)H where  is the
deflection in radians form zero position. The control spring torque is 12 x 10–6 Nm per radian.
Calculate the scale position in radians for a current of 4A.
6.
The inductance of a moving iron ammeter in micro – henry is given by the expression L = 20 +
10 - 3 2 where  is the deflection in radians from zero position. Determine the deflection of ammeter
for a current of 10A if the spring constant is 8 x 10–6 Nm/rad
7.
The moving coil comprises of 100 turns of insulated copper wire wound on a former of length
3 cm and breadth 4 cm. The resistance of the coil is 2000 ohms. The field strength of the magnet is 600
lines / cm2. The torque exerted by the control spring is 0.02 gm-cm per degree. Estimate the deflection
of instrument when a voltage of 120V is applied across it
8.
A coil of moving iron voltmeter has a resistance of 300 ohms and an inductance of 1 H. The
series resistor is 2,200 ohms. The meter reads 250V when a direct voltage of 250V is applied. What
will be the reading when 250V at 50Hz is applied?
9.
A modified Wheatstone bridge network is constituted as follows: AB is a resistance in parallel
with resistance p, BC is a resistance Q in parallel with a resistance a, CD and DA are resistances R and
S respectively. The nominal values of P,Q and S are each of 10 Ω. With resistance R in the circuit,
balance is obtained with p = 30,000 Ω and q = 25,000 Ω. With R replaced by a standard resistance of
10 Ω, balance is obtained when p = 15,000 Ω and q = 40,000 Ω. Calculate the value of R.
10.
Pointer of moving coil instrument gives full scale deflection of 20mA. The potential difference
across the meter when carrying 20mA is 200 mV. This instrument is intended to be used on 200A for
full scale indication. Find out the shunt resistance required to achieve this. If the instrument is used as a
voltmeter for full scale reading with 1000V find out the series resistance to be connected in it
11.
The coil of a moving coil voltmeter is 4 x 3 cm wide and has 100 turns wound on it. The
control spring exerts a torque of 2.5 x 10–4 N-m, when the deflection is 50 divisions on scale. If the flux
density on the magnetic field in the air gap is 1T, estimate the resistance that must be put in series with
the coil to give 1V/div. Resistance of the voltmeter is 10,000V
12.
The inductance of a moving iron ammeter in micro – henry is given by the expression L = 10 +
2
5 -  where  is the deflection in radians from zero position. Determine the deflection of ammeter for
a current of 3 and 5A if the spring constant is 1.2 x 10–5 Nm/rad
13.
A 100V moving coil voltmeter gives a full scale deflection of 100 degree. The moving coil has
dimensions of 3 cm x 2.5 cm and number of turns equal to 75. The air gap flux is 0.12 wb/m 2.
Determine the swamping resistance of the voltmeter when the spring constant is 3.5 x 10 –7 Nm per
degree and the coil resistance is 5 ohms.
14.
A 20A dynamometer ammeter is controlled by springs having the spring constant of 5 x 10–6
Nm per degree. Determine the inductance of the instrument for full scale deflection of 100 degree.
Initial inductance is 2 micro henry and the change is linear.
15.
Two ammeters A and B have resistance of 1.2 ohms and 1.5 ohm respectively and both give
full scale deflection with a current of 150mA. Calculate the suitable values of shunts are placed in
parallel in a circuit in which the total current flowing is 15 A. Find the reading on each instrument.
16.
The coil of an instrument has a resistance of 2 ohms and the instrument reads upto 250V when
a series resistance of 5 Kohm is connected in series with it. Find (a) the current range of the instrument
when used as an ammeter with the coil connected across a shunt of resistance 2 milliohms and b) the
exact value of the shunt resistance for the instrument to give a full – scale deflection with the current of
75A
17.
A wattmeter with resistances of the two coils as 0.01 ohms and 1000 ohms is used to measure
the power supplied to a resistive load. The load current and load voltage may be taken as 20A and 30V
respectively. Show the two ways in which the voltage coil can be connected and find the error in the
reading in each case.
18.
A 230V single phase watthour meter has a constant load of 4A passing through it for 5 hours at
0.8 p.f. If the meter disc make 883 revolutions during this period, find the meter constant in revolutions
per kwh. If the power factor is unity, what number of revolutions will the disc make in the above time
19.
In a potentiometer measurement, a standard cell of 1.0186 V balances at 60cm of the slide
wire, while an unknown emf source balances at 90 cm. When a voltmeter of 250 ohm resistance is used
to measure the unknown emf, it reads 1.5V. Determine the internal resistance of the unknown source
20.
The resistance of one meter long slide wire of a potentiometer is 25 ohms, across which a
battery of 4.2V is connected to supply the potentiometer current. An another cell of 1.4V connected in
series with a 10 ohms resistor is balanced on the potentiometer. Determine the position of the slider.
21.
The voltage between two points in a d.c circuit is measured by a potentiometer that gives a
reading of 1.2V. A 20kohms per volt d.c voltmeter reads only 0.6V on its 2.5V range when connected
to the same two points in the circuit. Calculate the circuit resistance between the two points.
22.
The four arms of wheat stone bridge have the following resistances P = 100 ohms Q = 10 ohms
X = 50 ohms and S = 4 ohms. Calculate the current flowing through the galvanometer of 20 ohms
resistance when the supply voltage is 10V. What should be the resistance of X for no deflection in the
galvanometer?
23.
An AC bridge is balanced for the following parameters: the arm AB = 0.2micro farad, the arm
BC = 500 ohms, the arm CD unknown, arm DA 300 ohm in parallel with 0.1 micro farad. Find the
constants in series
24.
In a Wheatstone bridge, the ratio arms AB = 10 Ω and BC = 100 Ω; standard resistance across
CD = 10 Ω. The shunt across 10 Ω ratio arm has to be changed from 2230 to 27670 Ω, when the
resistor R2 was changed from R1 in the arm DA. Calculate in magnitude the difference between the
resistances of R1 and R2. The bridges is balanced in both the cases.
25.
The four arms of an AC bridge are given as follows Arm AB = 2 kilo ohms and 0.2 micro farad
in parallel, BC = 1.5 kilo ohm, CD = 500 ohm and 0.8 henry in series, DA = 2 kilo ohms. The
frequency of supply is 1 kHz and the voltage is 20V. The supply terminal are A and C. a) Is the bridge
balanced, If not find the new constants of the arm CD for the bridge to be balanced. b) Find the voltage
across the high impedance detector for the original bridge constants.
26.
The arm AB and BC of a bridge contain pure resistances of 1500 ohms and 1000 ohms
respectively. The unknown impedance is connected in the arm CD. The values of capacitance and
series resistance in the arm DA are adjusted to 0.1 micro farad and 10 ohm respectively for balance.
The supply with a voltage of 15V is connected between terminals B and D. The supply frequency is
1000 Hz. A) Find the unknown resistance b) Find the voltage across a high impedance detector
connected across A and C. If the resistance of the arm BC is changed to 1010 ohms
27.
Four arm of the bridge are given below: Arm AB, R = 1000 ohms and C = 0.159 micro farad in
parallel, BC = 1000 ohms, CD = 500 ohms and DA = unknown resistance and 0.636 in series a) Find the
frequency for which the bridge is in balance. B) Find the value of unknown in the arm DA
28.
An impedance bridge is arranged as follows: the arm AB = unknown inductive coil, BC = 100
ohms, arm CD = 300 ohms and the arm CE = 0.75 micro farad arm ED = 3000 ohms and DA = 300
ohms. Calculate the resistance and inductance of the coil.
29.
The four arms of a bridge contain the following elements AB is an unknown air cored reactor
BC a 450 ohm resistor, CD a 1250 ohm resistor shunted by a loss – free capacitor of 1.02 micro farad,
DA a 500 ohm resistor. All the resistors are non – inductive and bridge is balance with the above
mentioned elements. An a.c supply of 1000Hz is connected to points A and C of the bridge and a
detector to points B and D. By deriving the balance conditions for the bridge circuit determine a) the
resistance and b) the inductance of the unknown reactor. Draw a vector diagram to represent the
conditions at balance.
30.
The four arms of an a.c bridge contains the following elements AB = a coil of unknown
impedance, BC a non – inductive resistor of 1000 ohms, CD a non – inductive resistor of 833 ohms in
series with a standard capacitor of 0.38 micro farad. DA non reactive resistor of 16800 ohms. The
supply frequency of 50 Hz is connected to points A and C and a detector to points B and D. Determine
the inductance and resistance.
31.
An Anderson bridge is arranged as follows: arm AB and BC consists of non- inductive
resistances of 600 ohms each, the arm BE and CD of non – inductive variable resistances, the arm EC of
a capacitor of 1 micro farad, arm DA of an inductive resistance. The a.c supply is given to A and C and
the detector to E and D. A balance is obtained when the resistance of the arm CD is 800 ohms and that
of the arm BE is 400 ohms. Calculate the resistance and inductance of the arm DA.
32.
The four arm of a Schering bridge are arranged as arm AB = imperfect capacitor, BC of a
resistance of 20000 ohms, CD of a resistance of 1200 ohms shunted by a capacitor of 300 pico farad,
DA of a standard capacitor of 0.05 micro farad. All the resistors are non – inductive. The supply of 1
kHz is connected to points A an dC and the detector to points B and D. Calculate a) the capacitance, b)
the equivalent series and c) tan.
33.
When testing a sample of insulating material balance was obtained with the following values of
elements in the arms of the bridge: 0.5 micro farad in parallel with 1000/ ohms resistor in arm CD, 260
ohms in arm BC and standard 106 pico farad in arm DA. The frequency of supply was 50Hz. Calculate
a) the capacitance b) the equivalent series resistance and c) tan  for the specimen
34.
A resistive position transducer has a shaft stroke of 10cm. The total resistance of the
potentiometer is 5000 ohms and the applied voltage is 50 V. When the wiper is at 2 cm from down,
what is the value of the output voltage measured by the voltmeter a) when the voltmeter has infinite
resistance, b) when it has 1 kilo ohm resistance.
35.
An a.c. LVDT has the following data: input 6.3V output 5V and range 2.5cm. Determine a)
the output voltage when the core is 1.75cm from centre b) the plot of output voltage versus core position
for a core movement going from + 2 cm to – 1 cm.
36.
In a wheat stone R2 = R3 = 130 ohms, and R4 = 130 ohms when un-strained and R4 = 130.5
when strained. If the gage factor is 2, calculate the strain 1.12 x 10 –3
37.
What is the true value of current in the 15 kilo ohm resistor as shown, If an ammeter of 2 kilo
ohm resistance is used to measure the current in the 15kilo ohm resistance, what will it read? If a
loading accuracy of 99 percent is desired in measuring the current, what should be ammeter resistance
be.
38.
A moving coil milli voltmeter has a resistance of 200 ohms and the full scale deflection is
reached when a potential difference of 100mV is applied across the terminals. The moving coil has
effective dimensions of 30mm x 25mm and is wound with 100 turns. The flux density in the gap is 0.2
wb/m2. Determine the control constant of the spring if the final deflection is 100 degree and a suitable
diameter of copper wire for the coil winding if 20 percent of the total instrument resistance is due to the
coil winding. Resistivity of copper is 1.7 x 10 –8 ohm meter.
39.
The coil of a measuring instrument has a resistance of 1 ohm, and the instrument has a full
scale deflection of 250 V when a resistance of 4999 ohms is connected in series with it. Find a) the
current range of the instrument when used as an ammeter with the coil connected across a shunt of 1/499
ohms and b) the value of the shunt resistance for the instrument to give a full scale deflection of 50A.
40.
A watthour meter is calibrated to measure energy on a 250V supply. On test a steady current
of 15A is passed through it for 5 hours at unity power factor. If the meter readings before and after the
test are 8234.21kwh and 8253.13 kWh respectively, calculate the percentage error. If the spindle turns
through 290 revolutions during 5 minutes when a current of 20A is passing through the meter at 250V
and 0.87 power factor, calculate the meter constant.
41.
The current and flux produced by series magnet of an induction watthour meter are in phase
but there is an angular departure of 3 degree form quadrature between voltage and the shunt magnet
flux. The speed of disc at full load and unity power factor is 40 rpm. Assuming the meter to register
correctly under this condition, calculate its speed at ¼ full load and 0.5 power factor lagging. Also find
the percentage error.
42.
An electrodynamometer type wattmeter has a field system which may be considered as long
compared with the diameter of moving coil, the mean diameter of moving coil is 30mm, and is wound
with 500 turns. If the current through the moving coil is 50mA and the wattmeter is measuring power
flowing in a circuit having a power factor of 0.7, estimate the torque, if the axes of the field and the
moving coils are at a) 45 degree and b) 90 degree.
43.
The pressure coil of an electrodynamometer wattmeter has a resistance of 6600 ohms. When
the voltage applied to the pressure coil is 120V and a current of 20A flows in the series coil, the
deflection is 160 degree. What additional resistance must be connected in the pressure coil circuit to
make the constant of the meter equal to 20W per degree?
44.
A 250V, 10A electrodynamometer wattmeter has a resistance of current and potential coils of
0.5 ohms and 12500 ohms. Find the percentage error due to each of the two methods of connections
with unity power factor at 250V with current a) 4A and b) 12A.
45.
The ratio arms of a Kelvin bridge are 100 ohms each. The galvanometer has an internal
resistance of 500 ohms and a current sensitivity of 200 mm/micro amps. The unknown resistance is
0.1002 and the standard resistance is set at 0.1000 ohms. A d.c current of 10 amps is passed through the
standard and the unknown resistance from a 2.2V battery in series with a rheostat. Calculate the
deflection of the galvanometer. Neglect the resistance of the link. Find also the resistance unbalance to
produce the deflection of 1mm
46.
A standard cell of 1.0185 V used with a simple potentiometer balances at 50cm. Calculate a)
the emf of the cell that balances at 72cm. b) the percentage error in voltmeter which balances at 64.5 cm
when reading 1.33V c) the percentage error in an ammeter that reads 0.43 A when balances at 43.2 cm
with the voltage drop across a 2 ohm resistor in the ammeter circuit.
47.
A slide wire potentiometer is used to measure the voltage between two points of a certain d.c
circuit. The potentiometer reading is 1 volt. Across the same two points when a 10,000 ohm/volt
voltmeter is connected, the indicated reading on the voltmeter is 0.5V on its 5V range. Calculate the
input resistance between two points.
48.
A slide wire potentiometer has a battery of 4V and negligible internal resistance. The
resistance of slide wire rheostat is adjusted so that balance is obtained when the sliding contact is at
101.8 cm. a) Find the working current of the slide wire and the rheostat setting. B) if the slide wire has
divisions marked in mm and each division can be interpolated to one fifty, calculate the resolution of the
instrument.
49.
The a.c bridge is used to measure an unknown inductance Lx that has inherent resistance Rx.
The bridge parameters are R1 = 20000 ohms, R2 = 500000 ohms C2 = 0.003 micro farad,  = 106 rad /s.
C1 is adjustable from 10 pF and R4 is adjustable from 0 to 10000 ohms. A) Show that the equations for
resistance and reactive balance are independent of each other. Derive expression for Rx and Lx in terms
of  R1, R2 R4 C1 and C2. b) determine the largest values of Rx and Lx that can be measured with the
given parameters
50.
The four arms of a bridge network are made up as follows ab, a resistor of 50 ohms in parallel
with an inductor of 0.1H, bc, a resistor of 100 ohms, cd, an unknown resistor R in parallel with an
unknown capacitor C, da a resistor of 1000 ohms, A 50 Hz voltage supply is applied across ac. Find R
and C when a vibration when a vibration galvanometer connected across bd is undeflected.
51.
A four branch bridge network ABCD balanced at 1000 Hz has branches AB and BC of pure
resistance of 1000 ohms and 1250 ohms respectively. An unknown impedance forms the arm CD and
the branch DA consists of a standard capacitor fo 0.1micro farad capacity and negligible resistance
connected in series with a non – inductive resistance of 10 ohms to give balance. The supply voltage is
15V and the supply is given at the points B and D. Find the components of unknown impedance.
52.
The circuit for measurement of effective resistance and self – inductance of an iron cored coil
is as follows: arm ab the unknown impedance, arm bc a pure resistance R3, arm cd, a lossless capacitor
C2. arm da a capacitor C2 in series with a resistance. Under balance condition R3 = 10 ohms, R2 = 842
ohms, C2 = 0.135 micro farad C4 = 1 micro farad. Calculate the value of effective resistance and self –
inductance at a supply frequency of 100 Hz. Derive equation for balance.
53.
A capacitor bushing forms arm ab of the Schering bridge and a standard capacitor of 500 pF
capacitance and negligible loss, forms arm ad, Arm bc consists of a non – inductive resistance of 300
ohms. When the bridge is balanced arm cd has a resistance of 72.6 ohms in parallel with a capacitance
of 0.148 micro farad. The supply frequency is 50Hz. Calculate the capacitance and dielectric loss angle
of capacitor.
54.
A Schering bridge is used for measuring the power loss in dielectrics. The specimens are in the
form of discs 0.3 cm thick and have a dielectric constant of 2.3. The area of each electrode is 314 cm2
and the loss angle is known to be 9 for a frequency of 50Hz. The fixed resistor of the network has a
value of 1000 ohms and the capacitance is 50pF. Determine the value of the variable resistor and
capacitor required.
55.
In a balanced bridge network, AB is a resistance of 500 ohms in series with an inductance of
0.18 H, BC and DA are non – inductive resistances of 1000 ohms and CD consists of a resistance R in
series with a capacitance C. A potential difference of 5Volt at a frequency of 5000/2 Hz is established
between the points A and C. Determine the values of R and C.
56.
The ratio arms of a Kelvin bridge are 100 ohms each. The galvanometer has an internal
resistance of 500 ohms and a current sensitivity of 200 mm/μA. The unknown resistance is 0.1002 and
the standard resistance is set at 0.1000 ohms. A d.c current of 10A is passed through the standard and
the unknown resistance from a 2.2 V battery in series with a rheostat. Calculate the deflection of the
galvanometer. Neglect the resistance of the link. Find also the resistance unbalance to produce a
deflection of 1mm.
57.
The inductance of a moving iron ammeter in micro – henry is given by the expression L = 10 +
5 – 2 where  is the deflection in radians from zero position. Determine the deflection of ammeter for
a current of 3 and 5A if the spring constant is 1.2 x 10–5 Nm/rad after deriving an expression for that
type of meter
58.
The four arms of a Wheatstone bridge are as follows. AB = 100Ω; BC = 10 Ω; CD = 4 Ω; and
DA = 50 Ω. The galvanometer has a resistance of 20 Ω and is connected across BD. A source of 10V
dc is connected across AC. Find the current through the galvanometer. What should be the resistance in
the arm DA for no current through the galvanometer
59.
A displacement capacitive transducer uses a differential arrangement with two outer plates
which are fixed and a central plate which is movable. The distance between fixed and movable plates is
5 mm when no displacement is applied. A voltage of 1000V rms is applied across the fixed plates. Find
the differential output voltage if a displacement of 0.01 mm is applied to the central plate. Find also the
sensitivity of the transducer.
60.
Two plates of parallel plate capacitive transducer are 30mm apart and the space is filled with
two different dielectric materials, one material is 1 cm thick with a dielectric constant of 5 and the other
material is 20mm thick with a dielectric constant of 10. If the capacitive transducer were to be made up
of single dielectric material what is the dielectric constant of the material.
61.
In a variable capacitive transducer, the diaphragms are 20mm in diameter and 4 mm apart. If a
pressure produces an average deflection of 0.25mm, calculate the value of capacitance after the
application of force. The capacitance before application of force is 400pG.
62.
A barium titanate crystal has dimensions of 5mm x 1.5 mm. The Young’s modulus of barium
titanate is 12 x 104 N/m2, its charge sensitivity is 150pV/N and permittivity is 112.5 x 10–9 F/m. A
capacitance of 10pF in parallel with 100MΩ resistance is connected across the crystal. Calculate the
rms value of voltage under open circuit and load conditions when a force of 0.0142sin100t newton is
applied to the crystal, calculate the rms value of deflection. The resistance of the crystal may be
neglected.
63.
The inductance of a moving iron ammeter with a full scale deflection of 90 at 1.5A, is given
by the expression L = (200+4θ2 – θ3) μH, where θ is the deflection in radian from the zero position.
Estimate the angular deflection of the pointer for a current of 1.0A.
64.
For a certain dynamometer ammeter the mutual inductance M varies with deflection θ
(expressed in degrees) as M = –6 cos(θ+30) mH. Find the deflecting torque produced by a direct
current of 50mA corresponding to a deflection of 60.
65.
In a particular instrument, the total resistance of the voltage coil circuit is 8200 Ω and the
mutual inductance changes uniformly from – 173μH at zero deflection to +175 μH at full scale, the
angle of full scale being 95. If a potential difference of 100V is applied across the voltage circuit, and
a current of 3A at a power factor if 0.75 is passed through the current coil, what will be the deflection, if
the spring control constant is 4.63 x 10–6 Nm/rad?