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.**

โ MCQ in AC Circuits Part 2 | REE Board Exam

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

Answer: **Option A**

Solution:

102.ย In Fig. 1.4, I_{1} + I_{2} is equal to ____.

A.ย ย 3 A

B.ย 4.33 A

C.ย 9 A

D.ย 3.43 A

Answer: **Option B**

Solution:

103.ย In Fig. 1.4, I_{2} + I_{3} is equal to _____.

A.ย 7 A

B.ย โ13ย ย A

C.ย 5 A

D.ย none of these

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

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

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

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

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

Answer: **Option D**

Solution:

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

A.ย i = I_{m} sin ฮธ

B. i = I_{m} sinย (ฮธย โ ฯ/2 )

C.ย ย i = I_{m} sinย (ฮธย + ฯ/2 )

D.ย ย i = I_{m} sinย (ฮธย + ฯ/4 )

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

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

Answer: **Option C**

Solution:

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

A.ย i = I_{m} sin ฮธ

B. i = I_{m} sinย (ฮธย โ ฯ/2 )

C.ย ย i = I_{m} sinย (ฮธย + ฯ/4 )

D.ย ย i = I_{m} sinย (ฮธย + ฯ/2 )

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

Answer: **Option B**

Solution:

114.ย An a.c. current given by iย =ย 14.14 sin (ฯt +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 โ30

D.ย 7.07, 210

Answer: **Option A**

Solution:

115.ย If e_{1} =ย A sin ฯt and e_{2} = B sin (ฯt โ ฯ), then

A.ย e_{1} legs e_{2}, by ฮธ

B.ย e_{2} lags e_{1} by ฮธ

C.ย e_{2} leads e_{1}, by ฮธ

D.ย e_{1} is in phase with e_{2}

Answer: **Option A**

Solution:

116.ย From the two voltage equations e_{A}ย = E_{m}ย sin 100ฯt and e_{B}ย = E_{m}ย sin (100ฯtย + ฯ/6), it is obvious that

A.ย e_{A} leads e_{B} 30ยฐ

B.ย e_{B} achieves its maximum value 1/600 second before e_{A} does

C.ย e_{B} lags behind e_{A}

D.ย e_{A} achieves its zero value 1/ 600 before e_{B}

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

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

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

Answer: **Option B**

Solution:

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

A.ย 105

B.ย 75

C.ย 15

D.ย 60

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

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

Answer: **Option A**

Solution:

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

A.ย 20

B.ย 5

C.ย 2.5

D.ย 40

Answer: **Option B**

Solution:

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

A.ย 10

B.ย 0

C.ย โ50

D.ย 5

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 5โ2

B.ย ย 2.5โ2

C.ย 5/ฯ

D.ย 0

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

Answer: **Option A**

Solution:

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

A.ย โ2ย A

B.ย 1 A

C.ย ย ย 1/โย 2 A

D.ย โ3ย A

Answer: **Option A**

Solution:

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

A.ย โ17 V

B.ย 5 V

C.ย 7 V

D.ย (3 + 2โ2 ) V

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

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

Answer: **Option A**

Solution:

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

A.ย ย 2โ6ย A

B.ย ย 6โ2ย A

C.ย โ(4/3)ย A

D.ย 1.5 A

Answer: **Option A**

Solution:

132.ย If i_{1} = 120 cos (100ฯt + 30ยฐ) and i_{2} = -0.1 cos (100ฯt + 100ยฐ) then i_{2} leads i_{1} by ____.

A.ย -110 degrees

B.ย 60 degrees

C.ย -60 degrees

D.ย 110 degrees

Answer: **Option A**

Solution:

133.ย If v_{1} = sin (ฯt + 30ยฐ) and v_{2} = -5 sin (ฯt – 15ยฐ) then v_{1} leads v_{2} by ____.

A.ย 225 degrees

B.ย 30 degrees

C.ย 45 degrees

D.ย none of these

Answer: **Option A**

Solution:

134.ย The rmsย value of a rectangular wave of period T, having a value of +V for a duration, T_{1} (<T) and โV for the duration T – T_{1} = T_{2} equals ____.

A.ย V

B.ย (T_{1} – T_{2})/T*V

C.ย V/โ2

D.ย (T_{1}/T_{2})* V

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/โ2

D.ย โ2

Answer: **Option A**

Solution:

136.ย Forย theย voltageย waveformย v(t)ย =ย 2ย +ย cosย (ฯtย +ย 180ยฐ)ย findย theย ratioย of V_{rms}/V_{ave}.

A.ย 3/2โ2

B.ย โ3/2

C.ย ฯ/2

D.ย ฯ

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 Aโ2

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

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

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

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 50โ2ย V, 50 Hz

D.ย ย ย 50โ2ย V, 100 Hz

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 ฯt axis.

A.ย 70.71 V

B.ย 100 V

C.ย 50 V

D.ย 141.42 V

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

Answer: **Option A**

Solution:

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

A.ย 31.8 A

B.ย 25 A

C.ย 38.2 A

D.ย 51.43 A

Answer: **Option C**

Solution:

145.ย For 200 V_{rms} 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

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

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

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

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

Answer: **Option B**

Solution:

150.ย Three alternating currents are given by i_{1}ย = 141 sin (ฯt + 45ยฐ) A; i_{2}ย = 30 sin (ฯtย +ย 90ยฐ)ย A;ย i_{3}ย =ย 20ย cosย (ฯtย โย 120ยฐ)ย A.ย Findย theย equationย ofย theย resultant current.

A.ย 167.4 sin (ฯt + 45.66ยฐ)

B.ย 74.6 sin ฯt

C.ย 143.8 sin (ฯt + 51.4ยฐ)

D.ย 64.7 sin (ฯt โ 30ยฐ)

Answer: **Option A**

Solution:

โ MCQ in AC Circuits Part 4 | REE Board Exam

#### Questions and Answers in AC Circuits

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

**MCQ in AC Circuits**

**MCQ from Number 1 โ 50**Answer key:

**included**

**MCQ from Number 51 โ 100**Answer key:

**included**

**MCQ from Number 101 โ 150**Answer key:

**included**

**MCQ from Number 151 โ 200**Answer key:

**included**

**MCQ from Number 201 โ 250**Answer key:

**included**

**MCQ from Number 251 โ 300**Answer key:

**included**

**MCQ from Number 301 โ 350**Answer key:

**included**

**MCQ from Number 351 โ 400**Answer key:

**included**

**MCQ from Number 401 โ 450**Answer key:

**included**

**MCQ from Number 451 โ 500**Answer key:

**included**

**MCQ in AC Circuits Series**

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