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# MCQ in AC Circuits Part 3 | REE Board Exam

This is the Multiple Choice Questions Part 3 of the Series in AC Circuits as one of the Electrical Engineering topic. In Preparation for the REE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Exam Questions in Electrical Engineering field, Electrical Engineering Books, Journals and other Electrical Engineering References.

#### Continue Practice Exam Test Questions Part 3 of the Series

SINUSOIDAL VOLTAGE AND CURRENT

Choose the letter of the best answer in each questions.

101.ย  Each of the three coils generates an e.m.f. of 230 V. The e.m.f. of second leadsย  thatย  ofย  theย  firstย  120 Vย  andย  theย  thirdย  lagsย  behindย  theย  firstย  byย  theย  same angle. The resultant e.m.f. across the series combination of the coils is ______.

A.ย  0 V

B.ย  230 V

C.ย  690 V

D.ย  none of these

View Answer:

Answer: Option A

Solution:

102.ย  In Fig. 1.4, I1 + I2 is equal to ____.

A.ย ย  3 A

B.ย  4.33 A

C.ย  9 A

D.ย  3.43 A

View Answer:

Answer: Option B

Solution:

103.ย  In Fig. 1.4, I2 + I3 is equal to _____.

A.ย  7 A

B.ย  โ13ย ย  A

C.ย  5 A

D.ย  none of these

View Answer:

Answer: Option C

Solution:

104.ย  In Fig. 1.5, E1 + E2 + E3 + E4 is equal to

A.ย  7 V

B.ย  5 V

C.ย  20 V

D.ย  none of these

View Answer:

Answer: Option B

Solution:

105.ย  In Fig. 1.5, ______ will have the least value.

A.ย  E1 + E2 + E3 + E4

B.ย  E1 + E2 + E3 โ E4

C.ย  E1 + E2 – E3 โ E4

D.ย  -E1 + E4

View Answer:

Answer: Option A

Solution:

106.ย  In a pure resistive a.c. circuit, the frequency of power curve is ____ that of the circuit frequency.

A.ย  half

B.ย  twice

C.ย  thrice

D.ย  same as

View Answer:

Answer: Option B

Solution:

107.ย  In a pure resistive circuit, the instantaneous voltage and current are given by:

v = 250 sin 314t volts

i = 10 sin 314t amperes

The peak power in the circuit is

A.ย  1250 W

B.ย  25 W

C.ย  2500 W

D.ย  250 W

View Answer:

Answer: Option C

Solution:

108.ย  In a pure resistive circuit, the instantaneous voltage and current are given by:

v = 250 sin 314t volts

i = 10 sin 314t amperes

The average power in the circuit is

A.ย  2500 W

B.ย  250 W

C.ย  25 W

D.ย  1250 W

View Answer:

Answer: Option D

Solution:

109.ย  An alternating voltage v = Vm sin ฮธ is applied to a pure inductive circuit. The current equation will be

A.ย i = Im sin ฮธ

B. i = Im sinย (ฮธย โ ฯ/2 )

C.ย ย i = Im sinย (ฮธย + ฯ/2 )

D.ย ย i = Im sinย (ฮธย + ฯ/4 )

View Answer:

Answer: Option B

Solution:

110.ย  The inductive reactance of a circuit is ____ frequency.

A.ย  directly proportional to

B.ย  inversely proportional

C.ย  independent of

D.ย  none of these

View Answer:

Answer: Option A

Solution:

111.ย  Power absorbed in a pure inductive circuit is zero because

A.ย  reactive component of current is zero

B.ย  active component of current is maximum

C.ย  power factor of the circuit is zero

D.ย  reactive and active component of current cancel out

View Answer:

Answer: Option C

Solution:

112.ย  An alternating voltageย v = Vm sin ฮธ is applied to a pure capacitive circuit. The current equation will be

A.ย i = Im sin ฮธ

B. i = Im sinย (ฮธย โ ฯ/2 )

C.ย ย i = Im sinย (ฮธย + ฯ/4 )

D.ย ย i = Im sinย (ฮธย + ฯ/2 )

View Answer:

Answer: Option D

Solution:

113.ย  The capacitive reactance of a circuit is ____ frequency.

A.ย  independent of

B.ย  inversely proportional to

C.ย  directly proportional to

D.ย  none of the above

View Answer:

Answer: Option B

Solution:

114.ย  An a.c. current given by iย  =ย  14.14 sin (ฯt +ย  ฯ/6) has an rms value of ____ amperes and a phase of ____ degrees.

A.ย  10, 30

B.ย  14.14, 180

C.ย  1.96ย  ,ย โ30

D.ย  7.07, 210

View Answer:

Answer: Option A

Solution:

115.ย  If e1 =ย  A sin ฯt and e2 = B sin (ฯt โ ฯ), then

A.ย  e1 legs e2, by ฮธ

B.ย  e2 lags e1 by ฮธ

C.ย  e2 leads e1, by ฮธ

D.ย  e1 is in phase with e2

View Answer:

Answer: Option A

Solution:

116.ย  From the two voltage equations eAย  = Emย  sin 100ฯt and eBย  = Emย  sin (100ฯtย  + ฯ/6), it is obvious that

A.ย  eA leads eB 30ยฐ

B.ย  eB achieves its maximum value 1/600 second before eA does

C.ย  eB lags behind eA

D.ย  eA achieves its zero value 1/ 600 before eB

View Answer:

Answer: Option B

Solution:

117.ย  The r.m.s. value a half-wave rectified current is 10 A, its value for full wave rectification would be ____ amperes.

A.ย  20

B.ย  14.14

C.ย  20/ฯ

D.ย  40/ฯ

View Answer:

Answer: Option B

Solution:

118.ย  A resultant current is made of two components: a 10 A d.c. components and aย  sinusoidal componentย  ofย  maximumย  valueย  14.14ย  A.ย  The averageย  valueย  of the resultant current is ____ amperes and r.m.s. value is ____ amperes.

A.ย  0, 10

B.ย  24, 24.14

C.ย  10, 14.14

D.ย  4.14, 100

View Answer:

Answer: Option C

Solution:

119.ย  The r.m.s. value of sinusoidal ac current is equal to its value at an angle of ____ degree.

A.ย  60

B.ย  45

C.ย  30

D.ย  90

View Answer:

Answer: Option B

Solution:

120.ย  Two sinusoidal currents are given by the equations: i1 = 10 sin (ฯt + ฯ/3) and i2 = 15 sin (ฯtย – ฯ/4). The phase difference between them is ____ degrees.

A.ย  105

B.ย  75

C.ย  15

D.ย  60

View Answer:

Answer: Option A

Solution:

121.ย  Aย  sineย  waveย  hasย  aย  frequencyย  ofย  50ย  Hz.ย  Itsย  angularย  frequencyย  isย  ____ radian/second.

A.ย  50/ฯ

B.ย  50/2ฯ

C.ย  50ฯ

D.ย  100ฯ

View Answer:

Answer: Option D

Solution:

122.ย  An a.c. current is given by i = 100 sin 100. It will achieve a value of 50 A after ____ second.

A.ย  1/600ย  C.ย  1/1800

B.ย  1/300ย  D.ย  1/900

View Answer:

Answer: Option A

Solution:

123.ย  The reactance offered by a capacitor to alternating current of frequency 50 Hzย  isย  10ย โฆ.ย  Ifย  frequencyย  isย  increasedย  toย  100ย  Hzย  reactanceย  becomesย  ____ ohm.

A.ย  20

B.ย  5

C.ย  2.5

D.ย  40

View Answer:

Answer: Option B

Solution:

124.ย  A complex current wave is given by i = 5 + 5 sin 100ฯt ampere. Its average value is ____ ampere.

A.ย  10

B.ย  0

C.ย  โ50

D.ย  5

View Answer:

Answer: Option D

Solution:

125.ย  Theย  currentย  throughย  aย  resistorย  hasย  aย  waveย  formย  asย  shown inย  Fig.ย  1.6.ย  The reading shown by a moving coil ammeter will be ____ ampere.

A.ย ย 5โ2

B.ย ย 2.5โ2

C.ย  5/ฯ

D.ย  0

View Answer:

Answer: Option C

Solution:

126.ย  A constant current of 2.8 exists in a resistor. The rms value of current is

A.ย  2.8 A

B.ย  about 2 A

C.ย  1.4 A

D.ย  undefined

View Answer:

Answer: Option A

Solution:

127.ย  The rms value of a half-wave rectified symmetrical square waveย  current of 2 A is

A.ย  โ2ย  A

B.ย  1 A

C.ย ย ย 1/โย 2 A

D.ย  โ3ย  A

View Answer:

Answer: Option A

Solution:

128.ย  The rms value of the voltage v(t) = 3 + 4 cos (3t) is

A.ย  โ17 V

B.ย  5 V

C.ย  7 V

D.ย  (3 + 2โ2 ) V

View Answer:

Answer: Option A

Solution:

129.ย  The rms value of the resultant current in a wire which carries a dc current of 10 A and a sinusoidal alternating current of peak value 20 A is

A.ย  14.1 A

B.ย  17.3 A

C.ย  22.4 A

D.ย  30.0 A

View Answer:

Answer: Option B

Solution:

130.ย  For the triangular waveform in the figure, the rms value of voltage is equal to

A.ย  โ(1/6)ย V

B.ย  โ(1/3) V

C.ย  1/3 V

D.ย  โ(2/3) V

View Answer:

Answer: Option A

Solution:

131.ย  The rms value of the periodic waveform given in the figure is

A.ย ย  2โ6ย  A

B.ย ย  6โ2ย  A

C.ย  โ(4/3)ย  A

D.ย  1.5 A

View Answer:

Answer: Option A

Solution:

132.ย  If i1 = 120 cos (100ฯt + 30ยฐ) and i2 = -0.1 cos (100ฯt + 100ยฐ) then i2 leads i1 by ____.

A.ย  -110 degrees

B.ย  60 degrees

C.ย  -60 degrees

D.ย  110 degrees

View Answer:

Answer: Option A

Solution:

133.ย  If v1 = sin (ฯt + 30ยฐ) and v2 = -5 sin (ฯt – 15ยฐ) then v1 leads v2 by ____.

A.ย  225 degrees

B.ย  30 degrees

C.ย  45 degrees

D.ย  none of these

View Answer:

Answer: Option A

Solution:

134.ย  The rmsย  value of a rectangular wave of period T, having a value of +V for a duration, T1 (<T) and โV for the duration T – T1 = T2 equals ____.

A.ย  V

B.ย  (T1 – T2)/T*V

C.ย  V/โ2

D.ย  (T1/T2)* V

View Answer:

Answer: Option A

Solution:

135.ย  The rms value of the voltage waveform v(t) = sin 10t + sin 20t is ____.

A.ย  1

B.ย  1/2

C.ย  1/โ2

D.ย  โ2

View Answer:

Answer: Option A

Solution:

136.ย  Forย  theย  voltageย  waveformย  v(t)ย  =ย  2ย  +ย  cosย  (ฯtย  +ย  180ยฐ)ย  findย  theย  ratioย  of Vrms/Vave.

A.ย 3/2โ2

B.ย  โ3/2

C.ย  ฯ/2

D.ย  ฯ

View Answer:

Answer: Option A

Solution:

137.ย  The rms value of the periodic wave form e(t) shown in the figure is _____.

A.ย ย  Aโ(3/2)ย ย ย ย  C.ย  Aโ(1/3)

B.ย ย  Aโ(2/3)ย ย ย ย  D.ย ย Aโ2

View Answer:

Answer: Option B

Solution:

138.ย  Which of the waveforms are having unity peak factor?

A.ย  figure a and b

B.ย  figure b and c

C.ย  figure a and c

D.ย  none of these

View Answer:

Answer: Option B

Solution:

139.ย  The length of time between a point in one cycle to the same point of the next cycle of an AC wave is the ______.

A.ย  frequency

B.ย  period

C.ย  magnitude

D.ย  polarity

View Answer:

Answer: Option B

Solution:

140.ย  In an experiment, a sinusoidal wave form is observed to complete 8 cycles in 25 msec. Determine the frequency of the wave form.

A.ย  320 Hz

B.ย  40 Hz

C.ย  200 Hz

D.ย  64 Hz

View Answer:

Answer: Option A

Solution:

141.ย  If emf in a circuit is given by e = 100 sin 628t, the maximum value of voltage and frequency is ______.

A.ย  100 V, 50 Hz

B.ย  100 V, 100 Hz

C.ย ย ย 50โ2ย  V, 50 Hz

D.ย ย ย 50โ2ย  V, 100 Hz

View Answer:

Answer: Option B

Solution:

142.ย  A sinusoidal voltage wave has an RMS value of 70.71 V and a frequency of 60ย  Hz.ย  Determineย  theย  valueย  ofย  theย  voltageย  0.0014ย  secondย  afterย  theย  wave crosses the ฯt axis.

A.ย  70.71 V

B.ย  100 V

C.ย  50 V

D.ย  141.42 V

View Answer:

Answer: Option C

Solution:

143.ย  Anย  alternatingย  currentย  varyingย  sinusoidallyย  withย  frequencyย  ofย  50ย  Hzย  hasย  an RMS value of 20 A. At what time measured from the positive maximum value will the instantaneous current be 14.14 A?

A.ย  1/600 sec

B.ย  1/200 sec

C.ย  1/300 sec

D.ย  1/400 sec

View Answer:

Answer: Option A

Solution:

144.ย  The average value of the function i = 50 sin ฯt + 30 sin 3ฯt is equal to ______.

A.ย  31.8 A

B.ย  25 A

C.ย  38.2 A

D.ย  51.43 A

View Answer:

Answer: Option C

Solution:

145.ย  For 200 Vrms value triangular wave, the peak value is equal to ______.

A.ย  200 V

B.ย  222 V

C.ย  282 V

D.ย  346 V

View Answer:

Answer: Option D

Solution:

146.ย  Determineย  theย  rmsย  valueย  ofย  aย  semi-circularย  currentย  waveย  whichย  hasย  a maximum value of A.

A.ย  0.816 A

B.ย  0.23 A

C.ย  0.866 A

D.ย  0.707 A

View Answer:

Answer: Option A

Solution:

147.ย  The rms value of a half-wave rectified current is 100 A. Its value for full-wave rectification would be ______ amperes.

A.ย  141.4 A

B.ย  200 A

C.ย  200/ฯ A

D.ย  400/ฯ A

View Answer:

Answer: Option A

Solution:

148.ย  A half-wave rectified sine wave has an average value of 100 amp. What is the effective value?

A.ย  157 A

B.ย  444 A

C.ย  70.71 A

D.ย  100

View Answer:

Answer: Option A

Solution:

149.ย  The form factor of a half-wave rectified alternating current is ______.

A.ย  1.11

B.ย  1.57

C.ย  1.73

D.ย  1.0

View Answer:

Answer: Option B

Solution:

150.ย  Three alternating currents are given by i1ย  = 141 sin (ฯt + 45ยฐ) A; i2ย  = 30 sin (ฯtย  +ย  90ยฐ)ย  A;ย  i3ย  =ย  20ย  cosย  (ฯtย  โย  120ยฐ)ย  A.ย  Findย  theย  equationย  ofย  theย  resultant current.

A.ย  167.4 sin (ฯt + 45.66ยฐ)

B.ย  74.6 sin ฯt

C.ย  143.8 sin (ฯt + 51.4ยฐ)

D.ย  64.7 sin (ฯt โ 30ยฐ)

View Answer:

Answer: Option A

Solution:

#### Questions and Answers in AC Circuits

Following is the list of practice exam test questions in this brand new series:

MCQ in AC Circuits
PART 1: MCQ from Number 1 โ 50                  Answer key: included
PART 2: MCQ from Number 51 โ 100              Answer key: included
PART 3: MCQ from Number 101 โ 150            Answer key: included
PART 4: MCQ from Number 151 โ 200            Answer key: included
PART 5: MCQ from Number 201 โ 250             Answer key: included
PART 6: MCQ from Number 251 โ 300             Answer key: included
PART 7: MCQ from Number 301 โ 350             Answer key: included
PART 8: MCQ from Number 351 โ 400             Answer key: included
PART 9: MCQ from Number 401 โ 450             Answer key: included
PART 10: MCQ from Number 451 โ 500           Answer key: included
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