This is the Multiple Choice Questions Part 4 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 4 of the Series

SINUSOIDAL VOLTAGE AND CURRENT

**Choose the letter of the best answer in each questions.**

โ MCQ in AC Circuits Part 3 | REE Board Exam

151.ย The maximum value of a sine wave AC voltage which will produce heat in a resistor at the same average rate as 115 V of direct current is ____.

A.ย 81.3 V

B.ย 115 V

C.ย 162.6 V

D.ย 230 V

Answer: **Option C**

Solution:

152.ย A sinusoidal voltage source has a peak value of 150 volts. What equivalent DCย voltageย sourceย wouldย produceย theย sameย heatingย effectย inย aย 1-ohm resistor?

A.ย 15 V

B.ย 212 V

C.ย 95 V

D.ย 106 V

Answer: **Option D**

Solution:

153.ย Theย effectiveย valueย ofย v(t)ย =ย 100ย +ย Aย sinย ฯtย isย knownย toย beย 103.1.ย The amplitude A of the sine term is ____.

A.ย 25

B.ย 4.85

C.ย 35.48

D.ย 100

Answer: **Option C**

Solution:

154.ย Anย alternating current and a direct current flow simultaneously in the same conductor. If the effective of the AC is 8 A and DC is 12 A, what will an AC ammeter read when connected in the circuit?

A.ย 14.42 A

B.ย 12 A

C.ย 11.66 A

D.ย 16.49 A

Answer: **Option A**

Solution:

155.ย Find the reading of an AC voltmeter connected across the series source of 100 sin (ฯt โ ฯ/2) and 100 sin ฯt.

A.ย 100

B.ย 130.65

C.ย 170.71

D.ย 184.78

Answer: **Option A**

Solution:

156.ย A voltage is given be v = 100 sin 314t. How long does it take this wave to complete one fourth of a cycle?

A.ย 20 ms

B.ย 10 ms

C.ย 5 ms

D.ย 1 ms

Answer: **Option C**

Solution:

157.ย When a 15 V square wave is connected across a 50 volt AC voltmeter, it will read _____.

A.ย 21.21 V

B.ย 10.61 V

C.ย 15 V

D.ย 9.55 V

Answer: **Option C**

Solution:

158.ย Calculateย theย effectiveย value ofย v(t) =ย 100ย sinย 400tย + 50 sinย 800tย +ย 10ย cos 1200t V.

A.ย 79.5 V

B.ย 57.9 V

C.ย 112.25 V

D.ย 121. 52 V

Answer: **Option A**

Solution:

159.ย Theย magneticย fieldย energyย of anย inductorย changesย fromย maximumย valueย to minimum value in 5 ms when connected to an ac source. The frequency of the source is

A.ย 20 Hz

B.ย 50 Hz

C.ย 200 Hz

D.ย 500 Hz

Answer: **Option B**

Solution:

160.ย Non-sinusoidal waveforms are made up of

A.ย different sinusoidal waveforms

B.ย fundamental and even harmonics

C.ย fundamental and odd harmonics

D.ย even and odd harmonics only

Answer: **Option A**

Solution:

161.ย The positive and negative halves of a complex wave are symmetrical when

A.ย it contains even harmonics

B.ย phase difference between even harmonics and fundamental is 0 or ฯ

C.ย it contains odd harmonics

D.ย phase difference between even harmonies and fundamental is either ฯ/2 or 3ฯ/2

Answer: **Option C**

Solution:

162.ย Theย r.m.s.ย valueย ofย theย complexย voltageย givenย by v = 16โ2 sin ฯt + 12โ2 sin 3ฯt is

A.ย 20โ2

B.ย 20

C.ย ย 28 โ2

D.ย 192

Answer: **Option B**

Solution:

163.ย Inย aย 3-phaseย system,ย ____thย harmonicย hasย negativeย phaseย sequenceย of RBY.

A.ย 9

B.ย 13

C.ย 5

D.ย 15

Answer: **Option C**

Solution:

164.ย Aย complexย currentย waveย isย givenย byย theย equation i = 14 sin ฯt + 2 sin 5ฯt . The r.m.s. value of the current is ____ ampere.

A.ย 16

B.ย 12

C.ย 10

D.ย 8

Answer: **Option C**

Solution:

165.ย When pure inductive coil is fed by a complex voltage wave, its current wave

A.ย has larger harmonic content

B.ย is more distorted

C.ย is identical with voltage wave

D.ย shows less distortion

Answer: **Option D**

Solution:

166.ย A complex voltage wave is applied across a pure capacitor. As compared to the fundamental voltage, the reactance offered by the capacitor to the third harmonic voltage would be

A.ย nine times

B.ย three times

C.ย one-third

D.ย one-ninth

Answer: **Option C**

Solution:

167.ย Whichย ofย theย followingย harmonicย voltageย componentsย inย aย 3-phaseย system would be in phase with each other?

A.ย 3rd, 9th, 15th etc.

B.ย 7th, 13th, 19th etc.

C.ย 5th, 11th, 17th etc.

D.ย 2nd, 4th, 6th etc.

Answer: **Option A**

Solution:

168.ย An alternating voltage is one that

A.ย varies continuously in magnitude

B.ย reverses periodically in polarity

C.ย never varies in magnitude

D.ย both A and B

Answer: **Option D**

Solution:

169.ย Oneย completeย revolutionย ofย aย conductorย loopย throughย aย magneticย fieldย is called a(n)

A.ย octave

B.ย decade

C.ย cycle

D.ย alternation

Answer: **Option C**

Solution:

170.ย For a sine wave, one half cycle is often called a(n)

A.ย alternation

B.ย harmonic

C.ย octave

D.ย period

Answer: **Option A**

Solution:

171.ย For a sine wave, the number of complete cycles per second is called the

A.ย period

B.ย wavelength

C.ย frequency

D.ย phase angle

Answer: **Option C**

Solution:

172.ย To compare the phase angle between two waveforms, both must have

A.ย the same amplitude

B.ย the same frequency

C.ย different frequency

D.ย both A and B

Answer: **Option B**

Solution:

173.ย The value of alternating current or voltage that has the same heating effect as a corresponding dc value is known as the

A.ย peak value

B.ย average value

C.ย rms value

D.ย peak-to-peak value

Answer: **Option C**

Solution:

174.ย For an ac waveform, the period refers to

A.ย the number of complete cycles per second

B.ย the length of time required to complete one cycle

C.ย the time it takes for the waveform to reach its peak value

D.ย none of these

Answer: **Option B**

Solution:

175.ย The wavelength of a radio wave is

A.ย inversely proportional to its frequency

B.ย directly proportional to its frequency

C.ย inversely proportional to its amplitude

D.ย unrelated to its frequency

Answer: **Option A**

Solution:

176.ย Unless indicated otherwise, all sine wave ac measurements are in

A.ย peak-to-peak values

B.ย peak values

C.ย rms values

D.ย average values

Answer: **Option C**

Solution:

177.ย Aย unitย stepย voltageย isย appliedย acrossย anย inductor.ย Theย currentย throughย the inductor will be

A.ย zero for all time

B.ย a step function

C.ย a ramp function

D.ย a delta (impulse) function

Answer: **Option C**

Solution:

178.ย Aย rampย currentย flowingย throughย anย initiallyย relaxedย capacitorย will resultย in a voltage across it that

A.ย varies inversely with time

B.ย remains constant

C.ย varies directly with time

D.ย varies as the square of time

Answer: **Option D**

Solution:

179.ย The voltage v(t) = t u(t) volts is connected across a 1 H inductor having an initial current of -1 A. The net current will be zero at time t equal to

A.ย 0

B.ย ย 1โ2ย seconds

C.ย โ2ย seconds

D.ย 1 second

Answer: **Option C**

Solution:

180.ย A voltage waveform v (t) = 12t^{2} is applied across 1H inductor for t โฅ 0, with initial current through itย being zero. The current through the inductor for tย โฅย 0 is given by

A.ย 12t

B.ย 24t

C.ย 12t^{3}

D.ย 4 t^{3}

Answer: **Option D**

Solution:

181.ย It is desired to have a constant direct current i(t) through the ideal inductor L. The nature of the voltage source v(t) must

A.ย constant voltage

B.ย linearly increasing voltage

C.ย an ideal impulse

D.ย exponentially increasing voltage

Answer: **Option C**

Solution:

182.ย For the current and voltage waveforms, identify the element & its value.

A.ย L, 25 H

B.ย C, 25 F

C.ย L, 2ย H

D.ย C, 2 F

Answer: **Option B**

Solution:

183.ย The voltage and current waveforms for an element are shown inย theย figure. Find the circuit element and its value.

A.ย L and 25 H

B.ย C and 25 F

C.ย L and 1 H

D.ย C and 1 F

Answer: **Option A**

Solution:

184.ย Whatย isย theย rmsย valueย ofย aย squareย waveย withย anย amplitudeย ofย 10ย Aย and frequency of 1 Hz?

A.ย 0 A

B.ย 10 A

C.ย 5 A

D.ย 7.07 A

Answer: **Option B**

Solution:

185.ย What is the frequency in kHz of a radio signal whose wavelength is 15 m?

A.ย 10,000

B.ย 20,000

C.ย 15,000

D.ย 20,500

Answer: **Option B**

Solution:

SERIES CIRCUITS

186.ย REE Board Exam September 2003

The following are in series R = 1,000 ฮฉ, L = .100 ฮผH and C = 20,000 pF. The voltageย acrossย theย circuitย isย 100ย V,ย 60ย kHz.ย Whatย isย theย totalย impedance expressed in ohms?

A.ย 1882 ohms

B.ย 1000 ohms

C.ย 2132 ohms

D.ย 1885 ohms

Answer: **Option B**

Solution:

187.ย REE Board Exam October 2000

A series circuit has an applied voltage of v = 220 sin (ฯt + 30ยฐ) and draws a current of i = 10 sin (ฯt – 30ยฐ). What is the average power and power factor of the circuit?

A.ย 1,905 W, 86.6% lagging

B.ย 1,905 W, 86.6% lagging

C.ย 2,200 W, 100%

D.ย 1,100 W, 50% lagging

Answer: **Option D**

Solution:

188.ย REE Board Exam September 2001

A coil has an impedance of 75.4 ฮฉ when connected a across a source of 60 Hz. The same coil yields an impedance of 54.8 ฮฉ when connected across a source having a different frequency of 30 Hz. What is the coilโs inductance?

A.ย 245.7 mH

B.ย 512.8 mH

C.ย 158.6 mH

D.ย 341.7 mH

Answer: **Option C**

Solution:

189.ย REE Board Exam April 1996

A circuit consists of a 4 ohms resistor and a 300 ฮผF capacitor in series. It is connected across a 60 Hz voltage source with a 500 V peak voltage. What is the phasor form of the current?

A.ย I = 19.57โ 57.5ยฐ A

B.ย I = 8.84โ 73.2ยฐ A

C.ย I = 36.5โ 65.7ยฐ A

D.ย I = 10.5โ 65.7ยฐ A

Answer: **Option C**

Solution:

190.ย REE Board Exam September 2000

Find the power in a circuit if i(t) = 10 sin (ฯtย –ย 30ยฐ) and v(t) = 220 sin (ฯt +30ยฐ).

A.ย 550 watts

B.ย 2200 watts

C.ย 1900 watts

D.ย 1500 watts

Answer: **Option A**

Solution:

191.ย REE Board Exam April 1997

A current of 2.5 A flows through a series circuit consisting of a 100 ฮฉ resistor andย anย unknownย capacitorย acrossย aย sourceย ofย 460ย V,ย 50ย Hz.ย Whatย isย the value of the capacitive reactance?

A.ย X_{C} = 91.86 ฮฉ

B.ย X_{C} = 39.19 ฮฉ

C.ย X_{C} = 154.45 ฮฉ

D.ย X_{C} = 184.0 ฮฉ

Answer: **Option B**

Solution:

192.ย REE Board Exam April 1995

In a series RC circuit the voltage across theย capacitor and the resistor are 60 volts and 80 volts respectively. The total voltage is

A.ย 70

B.ย 100

C.ย 140

D.ย none of these

Answer: **Option B**

Solution:

193.ย EE Board Exam October 1984

An industrial coil has a resistance of 32 ohms and reactance of 24 ohms and rated 440ย voltsย atย 60ย Hz.ย Aย factoryย will connectย theย coil toย aย 440ย V,ย 50ย Hz supply. Solve for the value of a series resistor needed to avoid over-current condition.

A.ย 2.07 ohms

B.ย 2.64 ohms

C.ย 2.44 ohms

D.ย 2.25 ohms

Answer: **Option B**

Solution:

194.ย REE Board Exam October 1998

Twoย relaysย eachย withย 20ย ohmsย resistanceย andย 0.16ย Hย inductanceย are connected in series. What is the equivalent impedance?

A.ย 20 + j102.2 ฮฉ

B.ย 20 + j95.32 ฮฉ

C.ย 40 + j120.63 ฮฉ

D.ย 40 + j25.32 ฮฉ

Answer: **Option C**

Solution:

195.ย EE Board Exam October 1990

Anย inductiveย coilย takesย aย currentย ofย 2ย Aย andย consumesย 160ย Wย when connected to a 240 V ac supply. A second coil when connected across the same supply takes 3 A and 500 W. Find the total power when the two coils are connected in series to this supply,

A.ย 144.56 W

B.ย 134.31 W

C.ย 150.22 W

D.ย 128.35 W

Answer: **Option A**

Solution:

196.ย EE Board Exam October 1985

A coil draws 1875 watts when connected to a 150 V dc source. It consumes 30.72 watts when use on a 240 V, 60 Hz ac source. Find the inductance of the coil.

A.ย 0.0255 H

B.ย 0.0341 H

C.ย 0.0153 H

D.ย 0.0240 H

Answer: **Option D**

Solution:

197.ย REE Board Exam October 1994

Aย currentย ofย 10ย Aย andย a powerย factorย ofย 0.8ย laggingย isย takenย formย aย single phase 250 volt supply. The reactive power of the system is

A.ย 1500 vars

B.ย 2000 vars

C.ย 2500 vars

D.ย none of these

Answer: **Option A**

Solution:

198.ย REE Board Exam October 1996

The resistor of 6 ฮฉ and unknown impedance coil in series draws 12 A from a 120 V, 60 Hz line. If the real power taken from the line is 1152 watts, what is the coil inductance?

A.ย 15.9 mH

B.ย 10 mH

C.ย 20 mH

D.ย 1.59 mH

Answer: **Option A**

Solution:

199.ย REE Board Exam April 1997

Determine the power factor angle in the series circuit which consists of R = 25 ฮฉ, L = 0.2 H, across a power supply of 200 V, 30 Hz.

A.ย 36.4ยฐ

B.ย 46.4ยฐ

C.ย 52.4ยฐ

D.ย 56.4ยฐ

Answer: **Option D**

Solution:

200.ย EE Board Exam April 1993

The impedance coils absorbs 250 watts whenย connected across 220 V, 60 Hz mains. It is then connected across 110 V, 25 Hz mains and also absorbs 250 watts. What is the inductance of the coil?

A.ย 0.125 H

B.ย 0.149 H

C.ย 0.154 H

D.ย 0.163 H

Answer: **Option B**

Solution:

โ MCQ in AC Circuits Part 5 | 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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