E
MULTIVECTOR REVIEW AND TRAINING CENTER
AC CIRCUITS
PART-SINGLE PHASE SYSTEM
EXERCISES:
REE-Sept. 2013
1.
The value of form factor for a pure sine wave is
B. 0.707
A. 1.414
0.637
REE-Sept. 20071 April 2016
2.
Wavelength
is
the
distance
traveled
by
an
electronic wave
D. 1.11
/
during
T
the
time
wavelength of 12 meters, what is the frequency?
A. 250 KHZ
B. 25 KHZ
C. 250 MHZ
of one
cycle.
ven
a
D. 25 MHZ
REE-April 2007
3. What is the complex expressionfor a given alternating current, i = 250 sin(uwt-25deg
D. 160+ j75
C. 227-j106
A. 227 +j106
B. 160-j75
4.
REE-Sept. 2010
In a single-phase circuit VA
to a referencee
+ j84.85 v and V 96.59 j25.88 v with respect
D. -11.74 +j110.73v
B. 11.74 +j110.73 v C. 11.74-j110.73 v
node 0. Calculate Vba
A. -11.74-j110.73 v
=
84.85
REE-October 2000
maximum
5. A sinusoidal current wave has a
A. 5
B. 12.7
REE-Sept. 2006/Sept. 2015
value of 20 A. What is the average
C. 14.14
the
6. When the sole purpose of ac is to produce heat,
of the curent.
B. Instantaneous
A. Average
7.
8.
selection of conductor is based
B. 115 V
on
value
D. Peak
C. RMS
which will produce
The maximum value of a sine wave AC voltage
rate as 115 V of direct current is
average
A. 81.3 VV
value of one-haf cycle?
D. 0
heat in a resistor at the same
C. 162.6 V
D. 230 V
same conductor. If the effective
curent flows simultaneously in the
direct
a
and
current
An alternating
connected in the circuit?
will an AC ammeter read when
what
12
is
A,
and
DC
A
8
is
AC
value of the
D. 16.49A
C. 11.66A
B. 12 A
A. 14.42 A
REE-April 2013
9. The power factor of incandescent bulb is
B. 0.8 leading
A. 0.8 lagging
REE Sept. 2016
10. The impedance triangle is similar to the.
the.
A. curent, resistor curent
C. voltage, impedance
11.
D. zero
C. unity
triangle with the resistance phasor in place of
B. current, resistor voltage
D. voltage, resistor voltage
REE Sept. 2018
+
what reactive power does the
When 3 A flows through a circuit with an input admitance of 0.4 j0.5 S,
circuit consumed?
A. 11 var
B.-8.7 var
C. 8.7 vaar
D.-11 var
AC Circuits 1
Page 1 of 11
MULTIVECTOR REVIEW AND
TRAINING CENTER
AC CIRCUITS
12, The effective
across
a
is
4-3 A. Calculate thecircuit element is (20 +
A. 50 watts &
i10) V and the
true and the
100
effective curent through the
reactive
C. 110 watts & 20 Vars
Vars
by the
element
voltage
lagging
lagging
B. 20 power taken
element.
100 Vars leading
D. 110watts&
watts & 20 Vars
leading
13. When the
current and
A. average
voltage are out of phase
by 90 degrees, the
B. zero
REE Sept. 2014
14. A 20 mH
inductor
A. 200sin100t
C. maximum
draws a current of
A. 0
uF capacitor is supplied with
=
C. 2000sin100t
REE-April 2013
a
=
B. leads
For an RL circuit, the
A. 0,1
equation.
D. 2000cos1001
B. 1.51 A voltage of v(t) 100 sin 377t. What is the
current at t 0
C. 3.02 AA
D. 1.07 A/
16. In a series RL circuit
the inductor current
A. lags
REE April 2016
17.
D. minimum
i(t) 100sin100t. Find the
voltage
B. 200cos100t
REE-Sept. 2016
15. A 40
power is
the resistor current.
C. is equal to
power factor cannot be less than
B. 1,0
18. An inductive coil consumes
What is the coil inductance?
A. 26 mH
D. is
D.-1,0
active power of 500 W and draws 10 A from a
B. 28 mH
negative of
orgreaterthan
C.0,-1
REE-April 2018
cY
C.30 mH
60 Hz ac supply of 110 v.
D. 32 mH
REE-Sept. 2017
19.The current in a series circuit of R
the source frequency in HZ?
A. 144.3
B. 163.5
10 ohm and L
60 mH
lags the applied voltage by 80°. What is
C. 150.4
D. 174.6
REE Sept. 2015
20. A series RL circuit is connected across a 120
v, 60 Hz source and draws a curent of 0.5 A of 0.70
lagging p.f. Determine the values of R and L.
A. R= 171 2, L= 0.455 H
B. R
171 Q, L= 0.445 H
REE
Sept. 2014/April 2017
C.R
168 Q, L =0.455 H
D. R
168 0, L
0.445 H
21. The net reactance in a series RLC circuit is
A.XL
B.Xc
C.X+X
D.X-Xc
REE- May 2008/Sept. 2017
22. A coil of inductance 0.1 H and resistance of 4 ohms is connected in seres with a condenser of 70.4
microfarad capacitance across a 60 Hz, 240 V line. How much current will flow on the circuit?
A. 55 A
B. 60 A
C. 57.5 A
D. 52.5 A
REE Sept. 2006
23.A 10 ohm resistor is connected in parallel to an inmpedance Z
3 + j4 ohms. Find the circuit power
factor.
A. 0.600 lagging
B.0.866 lagging
C.0.609 lagoing
D. 0.809 lagging
AC Circuits 1
Page 2 of 11
Circur Systen
yste
rt2
MULTIVECTOR REVIEW AND TRAINING CENTER
AC CIRCUITS
REE May 2009
24. A coil and
each have a 160
v
source. If they drawa1A
voltage across them when connected in series to 240 V, 60 HZ
cument from the
A. 25 ohms
source, what is the resistance
B. 10 ohms
of the co
C. 15 ohms
D. 20 ohms
REE October 1996
25. A
is rated 100
KVAR, 380 V, 50 Hz. What will ts
A. 50 KVAR
rating be at 60 Hz,
B. 40 KVAR
C. 90.9 KVAR
D. 57.7 KVAR
resistor
capacitor
26.
220V
REE April 2011
An inductive load draws a current of 6 A at
5x 10 F is connected in
08 pf. from a 208 v, 60 HZ source. f a
capacitor or
parallel with the load, what is overall
A. 0.85
the
p.f.?
B. 0.9
C. 1
D. 0.8
REE Sept. 2009
27.A single-phase motor is
What value of
factor to unity?
A. 214
taking 30 A, from a 220 v, 60 Hz
the power factor being 80%%
lagging
capacitor in microfarad connected across thesupply,
circuit will be
to raise tne
necessary
B. 220
C. 217
power
D. 224
REE-Feb. 2014
28. In a series RLC circuit, the
impedance at resonance is
A. maximum
B. minimum
C. infinity
D. zero
REE- Sept. 2012
29. What capacitance must be
placed in series with an inductance of 0.05 H so that at 100 Hz, the
impedance becomes equal to the ohmic resistance?
A. 50.7 F
B. 70.7 pF
C. 35.5 F
REE-Sept. 2010
30.A series RLC circuit resonates at 1,000 rad/sec. If C
D.87 uF
30 microfarads and it is known that the
impedance at resonanoe is 2.4 ohms, compute the value of Q of the circuit.
A. 13.9
B. 10.4
C. 20.8
D. 41.7
REE Sept. 2014
31.
20 mH is connected in parallel with a capacitance of 80 uF. What is the
frequency
An
inductance
of
when X Xc?
A. 100 H
B. 150 Hz
C. 128.5 Hz
D. 125.8 Hz
REE-April 2004
32. A tuned circuit is resonant at 4 MHz. Its Q is 100. What is its bandwidth?
A. 4 kHz
B. 400 kHz
C. 400 Hz
D. 40 kHz
REE - Sept. 2007
33. A circuit has load impedance Z= 50 + j80 Q. Detemine the parallel impedance required to correct the
power factor to unity.
A. 32 pF
B. 36 HF
C. 24 MF
D. 28 HF
SINGLE PHASE SYSTEM-SUPPLEMENTARY PROBLEMS
A
Voltage
wave is given by v= 100 sin314. How long does it take this wave form to complete one
fourth
cycle?
A 20 ms
B. 10 ms
C.5ms
D. 1 ms
2 When a 15 V square wave is connected across a 50-volt AC votmeter, it will read
A. 21.21 V
D. 9.55 V
B. 10.61 VM
C. 15 V
AC Circuts1
Page 3 of 11
6.
coil
If the voltage across e
coil are connected in series with a voltage source.
80°) A, what
2cos(866t
V and the curent flowing thru the resistor is
70)
+
10Sin(866t
resistance of the coil?
D. 4.33 Q
A resistor and a
is
ne
-
C.5 Q
B. 2.5 Q
A. 4.92 Q
individual
Current;
followin9
the
draws
value or
parallel
7. Ten
impedances
What is the eftective
5245°.
5L40°,
535°,
530,
520°, 525°, 5L10°, 5215°, 5L20°, 5225°,
in
Connected
the total current?
A. 48.444 A
8.
that
Problem 7, what is the equivalent impedance
Using
voltage is 100 sin150t V?
A.1.325L-30° Q
9.
10. Using Problem 7,
phase with the
power factor of the
source?
A. 54 mH
circuit?
connected across
what element should be
makes power available at a
current would be in
D. 31 mH
a c r o s s the
The open circuit voltage
is the maximum
is 500 j500 Q. What
pair of terminals.
11. A telephone circuit
looking into the terminals
terminals is 1 volt and the impedance
be drawn from the circuit?
power that can
C.0.001 Vw
A. 0.002 W
D. 0.8765
the circuit so that the
C. 13 mH
B. 25.4 mH
source
D. 1.462-22.5° Q
C. 0.707
B. 0.866
A. 0.924
could replace the impedances if the
C. 32.51L50° Q
B. 6.0262-2.5° Q
Using Problem 7, what is the equivalent
D. 84.389 A
C. 25.345 A
B. 34.255 A
B. 0.0005 W
D. 0.0014 W
on
20 Q. A 230 V is impressed
contactor is measured to be
a large magnetic
of
resistance
the inductance of the
ohmic
determine
12. The
core loss,
A.
3.2
Neglecting
as
taken
is
current
the contactor and the
contactor.
A. 261 mH
B. 183 mH
C. 315 mH
D. 251 mH
resistor is
inductance of 0.02 H. When a non-inductive
6 ohms and an
source is equal toO
13. A coil has a resistance of
drawn when connected to a 220 V DC
cument
the
the
with
coil,
connected in series
Detemine the resistance of the nonalone across a 220 V, 60 Hz source.
coil
the
drawn
L2
by
current
the
inductive resistor.
C. 3.69 a
A 3.63 2
B. 6.39
A.400 rad/sec
B. 500 rad/sec
D. 3.96 Q
When a sinusoidal voltage is applied,
= 0.02 H and an impedance of 17.85 Q.
L
has
circuit
RL
series
14. A
value of the angular frequency?
the curret lags the voltage by 63.5°. What is the
D. 800 rad/sec
C. 600 rad/sec
unknown
and an
consisting of a 100 0 resistor
15. A curent of 2.5 A flows through
the value of the capacitive reactance?
capacitor across a source of 460 V, 50 Hz. WhatC.is Xc
D. Xc 184.0 Q
154.45 Q
B. Xc 39.19 Q
A. Xc 91.86 Q
a series circuit
AC Circuits 1
Page 4 of 11
CircuitSystemns
rt2
r
t
2
MULTIVECTOR REVIEW AND TRAINING
Á6. A circuit consists of
AC CIRCUITS
CENTER
4
voltage source with a a500 QV resistor and 300 F
in series. It is
A. 1=19.7457.5°
peak voltage. What is capacitor
connected across a 60 Z
the phasor fom of
the current
B.I-8.84L73.20
17. A small
C.I 36.5L65.70
single phase, 240 V
D.I-10.5465.7
amperes and the total currentinduction motor is tested in
A: 800 W
is 3
parallel with 160 Q
Ine
B. 360 Wamperes. What is the power of the whole resistor.
moo c 2
circuit
18.
C. 220 W
A
D. 580 W
capacitor is placed in parallel
A
at bu lagging. What current inwith two inductive loads, one of 20 A at
30°
unity power factor?
amperes
A. 35.8 A
should flow in the
B. 44.6 A
lagging
the and
capacitor so thet
circut wueiavo
C. 28.8 A
19. A
D. 50.2 A
AC generator is
60%. If the total loss is
supplying power to a load of 3,200 W at 230 V and a
10% of the load, what
to 80%?
would be the savings in watts if the
power tactor is a e u
A. 64
B. 240
C. 427
D. 140
20. When a 240 V, 50 Hz
is applied to a
supply
parallel combination of 15Q resistor and
Current is 22.1
amperes. What must be the value
tne tota
of the frequency for a total current of 34
A. 25 Hz
B. 60 Hz
amperesr
C. 75 Hz
D. 100 Hz
21. A coil of 10 Q resistance
and 0.1 H inductance is
connected in parallel with a capacitor of
capacitance. If the total impedance of the combination
is 100 0, detemine the valueunknown
of the
capacitance.
A. 50 pF
B. 100 HF
C. 150 F
D. 200 F
22. A coil of 50 Q resistance and 150
mH, inductance is connected in parallel with a 50 HF
capacitor. Thee
source voltage is 100
sin(wt + 30°) V. What is the equation of the line current?
A. 1.91 sin(»t+ 52.5°)
B.
Single-phase
power rect
inductor,
1.25
C1.25 sin(ot-62°)
sin( ot+ 75.5°')
D. 1.32 sin(øt-75.5)
23. An impedance equal to 4.4/60° Q is connected across a
220 V source. What should be the value of
the second impedance in parallel with the
first, if the total power delivered to the circuit is to be 16.5
kWand the overall power factor is to be unity?
A. 2.21230.1°
B. 3.33-40.9°Q C. 5.63230° Q
D. 6.534-45°
24. An inductive reactance of 8 ohms is connected in
parallel with a
reactance of 18 ohms. This
combination is then connected in series with a variable resistance.capacitive
For what value of resistance will the
power factor be 0.5?
A. 8.314 Q
B. 3.138 Q
C. 13.81 Q
D. 1.381 0
25. What size of condenser must be
placed across an inductance
a resistance of 10 ohms and
reactance of 20 ohms to draw minimum current from the line having
when
the combination is connected
across a 60-cycle line?(Assume a condenser of negligible
resistance).
A. 20 uf
B. 106 uf
C. 10 uf
D.6.33 uf
26. A circuit draws 25 A when connected across a
source of frequency f. Determine the cument drawn by
the same circuit at resonance if f, is half the resonant
frequency.
A. 12.5 A
B. 17.68 A
C. 35.35 A
D. 50 A
27. A series RLC circuit is connected across a 120 V, 60 Hz source and draws a leading current of 5 A.
Detemine
the voltage across the capacitor at resonance if R 50 and L= 25 mH.
A. 47.12 V
B. 164.5 V
C. 236.6 V
D. 422.6 V
AC Circuits 1
Page 5 of 11
IVECTOR REVIEW AND TRAINING CENTER
MULTIVEC
AC CIRCUITS
of a
coll is given
heQ-factor
ratio of its
by
mum energy stored to its energy dissipated per cycle
factor
power
B.i t s
of ts power factor
C. the reCiprocal
D. the ratio of its resistance to its inductive reactance
a
A coil takes
apparent power and reactive power of 100 VA and 80
factor of the coil?
A. 1.33
B. 10
30. A coil is to be wound with Q-factor
VAR, respectively. What is the
8
D. 6
of
A lamp rated 120
V, 480 W is connected in series with the co
and connected across 230 V, 60 Hz
source. What is the
impedance of the coil if the voltage across tne
lamp is maintained at 120 V.
A. 35.2482.9° Q
B. 27.5272.4°
C. 45.5282.9° 2
D. 40.5272.4° N
8.
31. An inductive coil having a resistance of 25 ohms and inductance of 0.2 His connected in
parallel wrtn a
100 F capacitor. Find the frequency at which the total curent taken is in phase with the supply
voltage.
A. 35.6 Hz
B. 46.5 Hz
D. 52.9 Hz
C. 29.5 Hz
32. The series circuit of R = 3 0 and X = 4 Q and a parallel circuit of R and X have the same impedance
and power factor. Calculate the value of R' and X.
D. 5.62 0, 9.84 Q
B. 2.25 Q, 3.83 Q
C.7.47 Q, 7.51 Q
A. 8.33 Q, 6.25 0
branch has
33. A parallel circuit with one branch of R 5Q and a single unknown element in the other
8.23")A. The
I
following applied voltage and the current e 10cos(50t 60")V and =5.38cos(50t
unknown element is.
D.C 5 HF
B. L 0.02 H
C.C 10HF
A L 0.04 H
the
=
=
34. The voltage across the resistor, inductor and capacitor connected
respectively. What is the voltage across this circuit?
C. 100 V
B. 140 V
A. 160 V
in series is 60 V, 90 V, 10 V
consist of R
35. Detemine the power factor angle 6 in the series circuit which
power supply of 200 V, 30 HZ.
A. 36:4
B. 46.4
D. 50 V
=
C. 52.4
25 Q, L= 0.2 H, across a
D. 56.4
the power factor and the VARS.
B. 85.3%, 975 VARS
D. 42.3%, 1087 VARS
36. A load of 20 +j35 Q is connected across a 220 V source. Detemine
A. 49.6%, 1042 VARS
C52.2%, 1023 VARS
of resistor; take 4.8 kW from a 12037. An incandescent lamp load, generally considered to be made up
voft source. The instantaneous maximum value of power is
D. 480 watts
C. 2,400 watts
B. 9,600 watts
A. 4800 watts
. A factory takes 50 kW at 0.75 lagging power factor from a 480 V source. In order to raise the power
factor to 0.9 lagging. a synchronous motor rated 10 HP with an efficiency
power factor of the motor.
A. 0.476 lagging
B.0.825 lagging
C.0.476 leading
39. The wavelength of international distress of frequency is 600 m.
kHz?
A. 200
B. 300
C. 400
of 87.5% is used. Find the
D. 0.825 leading
What is the equivalent frequency
in
D. 500
AC Circuits1
Page 6 of 11
MULTIVECTOR REVIEW AND TRAINING CENTER
AC CIRCUTS
voltage across a given circuit is
75 + j50 V.
through it is (8 -j5) A?
Vnat is the
What
the power supplied to the circuit If the currernt
A 850 W
power sup
B. 550 WN
A resistor R and
an
capaCitor C are connected
C.750 W
D. 350 W
ammeter connected in the
in series
across a 100 V, 60
circuit is 2 A and
is 80 V.
cycle sou
the readina of a
Calculate the values of
A. 66 Q & 30 f
voltmeter
R and C.
co
B.30 0 & 60 uf
capacitor
42. The following are in
series: R
is 100 V. What
is the total
1,000 2. L=100 uH
and C
impedance
in
expressed
ohms if
B. 1000 Q
A. 1882 Q
43. A
C. 30 0 8& 66 uf
capacitor branch having a ratio of X to R
C. 2132 0
=
ted across the
D. 36 Q & 60 uf
20.o00 pF. The voltaga
the frequeny
n 1885 a
of 5 is
resistance and 3 Q inductive
paralleled with an impes
reactance. The power factor
size of the
of the resuting circue
in pf if the
capacitor
is 60 Hz.
frequency
A. 778.92 pf
B. 923.31 uf
C. 552.31 pf
leading. Find the
D. 392.13 uf
44. An
impedance of 3 - j3 Q is connected in parallel with 5 + i2 Q. The voltmeter connected acrosS d
resistance measures 45 V. Calculate the total
A 22.4 A
B. 41.3 A
current of the circuit.
C. 13.4 A
D. 7.91 A
45. The open circuit voltage of an altemator is 127 V and its internal impedance is 1040
.
Find the
voltage across a load of 302-30°Q.
A. 1002-9.7 V
B. 972-10° V
C. 79210° V
D. 1002-7.9° V
A6. The maximum instantaneous voltage and current output of an alternator are 300 V and 20 A,
respectively. What is the power output in watts if the voltage leads the current by30°?
D. 3000
A. 2598
C. 6000
B. 5196
47. The folilowing data are given for a series RL and a series RC which are connected in paralle!:
X = 15 Q, Xc =25 Q, Re
15 Q. For what value of R willthe circuit be in resonance?
B. 916 ohms
A. j 169 ohms
C.16.9 ohms
D. 91.6 ohms
of 0.2 H inductor and 74 pf capacitor is connected to
6.A series circuit composed
At what frequency will the current be 4 A with lagging power factor.
frequency source.
A. 47.767 Hz
B. 74.68 Hz
C. 60 Hz
a
60 V variable
D.50 Hz
30 ohm resistor is connected in parallel with an inductor of inductive reactance X. The combination
43. A
is then connected in series with a capacitor of reactance Xc. What is the value of XL and X¢ if the total
impedance is 1.92 ohms?
A 7.84, 7.34
B.47.4, 47.3
C. 44.8, 84.2
D. 84.7, 34.7
50. The phase shift between the voltageand current vectors is due to the following loads exceptone.
Amagnet coils
B. electric flat iron
C. power capacitors
D. fluorescent lampP
1 . The length of time between a point in one cycde to the same point of the next cycle
the
A. frequency
1
B. period
C. magnitude
of an AC wave Is
D. polarity
with frequency of 50 Hz has an RMS value of 200
52.An alternating current varying sinusoidally
A
instantaneous currentD.be1 /14.14
400 sec
time measured from the positive maximum value will the
A. 1/600 sec
B. 1/200 sec
A. At
ha
C. 1/300 sec
ACCircuits1
11
Page 7 of
TIVECTOR REVIEW
EW
AND 1TR
AC CIRCUITS
AINING CENTER
MULTIVECTO-
66. On
i/#)» n
M
MULTIVECTOR REVIEW AND TRAINING CENTER
AC CIRCUITS
(
has maxdmum value of 10 V and frequency of 1 cycle per second.
rectangular
53. An
aternating
What is the average value of the wave?
A. 5 V
a
a
wave
D. 7.07 V
C. 0
B. 10 V
54. Detemmine the ms value of a semi-circular current wave which has a maximum value of a.
D. 0.707a
A. 0.816 a
C. 0.866 a
B. 0.2377a
55. Find
the
reading
of
an
AC
voltmeter
connected
across
the
source
seies
of
100 sin (ot - t/2) and100 sin øt.
A. 100
B. 130. 65
D. 184.78
C. 170.71
56. A two-element series circuit has V = 240 + j0 volts and current 51.96-30 A. What is the current in
amperes which results when the resistance is reduced 50% ofits former value7
A. 68.57-j59.39
B. 68.57 + j59.39
C. 59.39- j68.57
D. 59.39 + j68.57
57 A 10 Q inductive resistor is connected in series with an unknown capacitance At 60 Hz theimpedance
of the circuit is 10 +j11.72. At 30 Hz the impedance of the circuit is 10-j5. What is the value of L in
2.
millihenrys?
D. 250
C. 100
B.500
50
5 8 . A 50 uf and 100 uf capacitors are connected in series and across a 100sin (øt + 30°) voltage. Write the
A5
ircu
25
O-6
eres
20
v
ge
equationof the current.
A1.26 sin (ot + 120°)
B. 1.26 sin(ot + 90) C. 5.65 sin(ot +120°)
59. Two impedances Za = 4 + j6 Q and Zg = 6 + j12 N are connected in parallel. The apparent power for
the impedance B is 1490 VA. Determine the total apparent power.
B. 3290 VA
A. 4250 VA
C. 2652 VA
inductance of A and resistance of B.
B. 0.215 H &3.8 Q
0.0132 H & 8.3 Q
A.
C.0.026 H& 12Q
power absorbed by the coil in watts.
B. 137.5 W
when supplied at
V, calculate the
C.51.37 W
D. 75.31 W
62. A series RLC circuit consists of 20 ohms resistance, 0.2 H inductance and an unknown capacitance.
has a leading angle of 45° at 60 Hz?
What is the value of the capacitance if the circuit
D. 30.7 uF
C. 27.8 uF
B. 47.9 uF
A. 35.18 F
83. Ife=100 sin(ot +30°) 50 cos 3ot 25 sin(5ot +150°)
5 sin(5ot-50°). Calculate the power in watts.
+
-
n
D. 0.031 H &5.3 Q
with a choking coil
61. A current of 5 A flows through a non-inductive resistance in seriesacross
the coil is 200
A. 168.75W
e
D. 8031 VA
of A is 5 Q
Two coils A and B are connected in series across a 240 V, 50 Hz supply. The resistance
60. and
the inductance of B is 0.015 H. If the input from the supply is 3 kW and 2 kVAR, find the
250 V, 50 Hz. If the voltage across the resistance is 120 V and
Se
D.5.65 sin(ot + 90°)
A. 1177
B.919
and i
C. 1043
=
20 sin(ot + 40°)+10 sin (3ot +30°)
D. 1224
64.A25 Q resistor connected in series with a coil of 50 Q resistance and 150 mH inductance.
power factor of the circuit?
B. 80%
A. 86%
C. 90%
What is the
D. 75 %
is to be corrected to unity
from a 230 V 50 Hz supply
65. A fluorescent lamp taking 80 W at 0.7 pf lagging
for this purpose?
in
be
should
placed
powerfactor. What element
D. parallel, 8.36 F
B. parallel, 4.95 F
C. series, 31.2 F
A. series, 59.4 F
AC Circuits 1
Page 8 of 11
MILTIVECTOR REVIEW AND TRAINING CENTER (M)
AC CIRCUITS
an ein 10° t A. What is the
80.
81.
66. One
MULTIVECTOR REVIEW AND
TRAINING CENTER
AC CIRCUITS
(
tuned circuit
has a
of the other
A. 6.33 x
leg in
10
Henry? capacitance of 1x 10°F. It is tuned at 200 kHz.
B. 20 x
What is the
10-3
67. A
C. 8.25 x 10
series
RLC
circuit
has
a
factor of the circuit
D. 120 x 10-3
resistance of 15 Q
at
A. 120
leg of a radio
inductance
82
9cond.
resonance?
B. 100
68. A
wo-element series circuit with R
unknown
angie. What is the
A-2.0
69.
Reactances are
reactance?
A. B0 Xc
and an
1,500 . What is the Q-
C. 140
=
D. 150
15 ohms, L =
20 mH has
an
frequency in Hz?
B. 21
connected in series:
B. 40 Xc
70. A feeder
inductive reactance of
C. 2,067
Xe
impedance of 30 ohms and an
D. 207
=
100, Xc2
=
40, XL1
=
30, XL2
=
70.
What
C. 60 XL
is the
net
supplies two loads, one at
D. 50 X
power factor.
50
The total
current supplied amperes at 50% power factor, the
A 180 A
by the feeder is
other 150
B. 200 A
amperes at unity
71. A fluorescent
C. 175 Aapproximately.
lamp
and
its
D.150 A
120
V, 60 Hz source.
inductive
What is the ballast draw a 1.0 A current at 50%
the fixture?
overall power factor
when a 26.5 uf lagging power factor from a
A. 0.832 lagging
is
72. A 50 Q
B.0.832 leading
resistance,
capacitor connected across
C.0.5 leading
30 Q inductive
D. 0.5 lagging
across a 100 V, 60
reactance and 25 Q
Hz
A. 65.726 Hz
supply. What will be its resonant
reactance are connected in
B. 53 Hz
series
C. 25 Hz
73. A 5 mH
pure inductance is
connected in parallel with one
circuit be in
microfarad capacitor. What
A. 250 Hz
frequency wil the
B. 2250 Hz
C. 60 Hz
74. A
D. 100 Hz
series circuit has
v and
amperes which results when the voltage V =
j0
I= 48
resistance is reduced to 50%current
A. Find the
A 46.20+ j69.20
of its former j36
in
value.
capacitive
frequency?
D.54.77 Hz
antiresonance?
two-element
240+
75. Find the value of an
A7.40-j15.00
76. The average value
A. 31.8 A
B.-46.20+ j69.20
impedance which requires-1,540 vars at 230 v
B. 16.82-j15.69
of the function i
B. 25 A
=
current
C. 46.20- j69.20
C. 17.09-j15.39
50 sin ot +30 sin 3ot is
C. 38.2 A
D.-46.20-j69.20
ms and 10 A
ms.
D. 17.62-j14.78
equal to
D.51.43 A
77. A circuit has
resistance of 20 2 and a reactance of 30 a.
A. 0
What is the power factor
B. 0.55
of the circuit?
C. 0.832
D.0.99
78. A capacitor in series w/
a 200 Q resistor draws
a current of 0.3
What is the value of
ampere from 120 volts, 60 Hz source.
capacitor in microfarad?
A. 8.7
B. 9.7
C.6.7
D. 7.7
79. Find the value of an
impedance which absorbs a complex power of 2300 VA with a
at 115 V ms.
30
A. 5+j7 2
B. 7 +j5 2
degrees angle
C. 5 +j3 Q
D. 3+j5 Q
A
MULTIVECTO
M
MULTIVECTOR REVIEW AND TRAINING CENTER M)
R
AC CIRCUITS
thru an inductor with inductance of 1 mH is given as i(t)
The Current
30. voltage
across this inductor?
AA00 sin 10°tv
6.
=
0.010 sin 10° t A. What is the
D. 100 cos 10 tv
C. 10 sin 10t v
B. 10 cos 10°tv
.
C of the circuit. If the
capacitive reactance Xo of a circuit varies inversely as the capacitance
capacitance of a certain circuit is decreased by 25%, by what percentage will Xo change?
What is the
Tne
A. 25% increase
82. What
are
the
i= 13.42 sin(
A. R
two
elements
in
a
series
D. 3 3 % increase
C. 66% increase
B. 20% increase
circuit
connection
having
a
current
and
votage
at is
or
500t 53.4' )A and v 150 sin( 500t+10
v?Q and L = 25 mH
B. R 6.3
and an
8.8 Q and L = 35 mH
C. R 7.5 Q and L= 30 mH
D. R
5 Q and L = 20 mH
83. Which is not 180 degrees apart?
AX and lc
B. Xc and lc
D.Xc and XL
C. and l
84. In an experiment, a sinusoidal wave form is observed to complete 8 cycles
frequency of the wave form.
B. 40 Hz
A 320 Hz
9
B. 10 A
D. 64 Hz
C. 200 Hz
nity
D. 7.07 A
C. 5 A
86. The rms value of a half-wave rectified current is 100 A. Its
amperes.
A. 141.4 A
B. 200 A
net
in 25 msec. Determine the
8 5 . What is the ms value of a square wave with an amplitude of 10 A and frequency of 1 Hz?
A0
value for full wave rectification would be
D. 40/T A
C. 200/m A
87. A half wave rectified sine wave has an average value of 100 amp.
C. 70.71 A
B. 444 A4
A. 157 A
What is the effective value?
88. Three alternating currents are given by i, =141 sin (ot + 45°: i2
30 sin (ot +90°), ia
=
D. 100 A
=
20 cos ( ot -120).
Find the equation of resultant current.
A. 167.4 sin (ot+45.66°)
B. 74.6 sin ot
C. 143.8 sin (øt+51.4°)
D. 64.7 sin (ot-30°)
89. A sinusoidal voltage source has a peak value of 150 volts. What equivalent
produce the same heating effect in a 1 ohm resistor?
C. 95 V
B. 212 V
A 15 V
DC voltage source would
D. 106 V
90. A series circuit has an applied voltage of V = 220sin(ot +30°) and draws a current 1=10sin(ot-30°).
What is the average power and power factor of
the circuit?
B. 1,905 W, 86.6% lagging
A. 1,905 W, 86.6% lagging
D. 1,100 W, 50% lagging
C 2,200 W, 100%
connected to a 150 v DC source. It consumes 3,072 watts when
91. A coil draws 1,875 watts whensource.
Find the inductance of the coil.
connected on 240 v, 60 Hz AC
D.0.0240H
B. 0.0153 H
C. 0.0341H
A0.0255H
and a vañable resistor. For what two values of
watts, if the impressed 60-cycle emf is 120
92. A series circuit consisting of a 66.2 uf capacitor172.8
circuit be
resistance will the power taken by the
volts?
A. 83.33 & 3.33 ohms
B.53.33& 30 ohms
the Q-
C. 5.33 & 3.0 ohms
D. 83.33 &5.33 ohms
AC Cirouits 1
Page 10 of 11