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MCQ in AC Circuits Part 7 | REE Board Exam

MCQ in AC Circuits Part 7 | REE Board Exam

This is the Multiple Choice Questions Part 7 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 7 of the Series

SERIES CIRCUITS

Choose the letter of the best answer in each questions.

MCQ in AC Circuits Part 6 | REE Board Exam

301.  A circuit component that opposes the change in circuit voltage is

A.  resistance

B.  capacitance

C.  inductance

D.  all of these

View Answer:

Answer: Option B

Solution:

302.  Power loss in an electrical circuit can take place in

A.  inductance only

B.  capacitance only

C.  inductance and resistance

D.  resistance only

View Answer:

Answer: Option D

Solution:

303.  A circuit of zero lagging power factor behaves as

A.  an inductive circuit

B.  a capacitive circuit

C.  R-L circuit

D.  R-C circuit

View Answer:

Answer: Option A

Solution:

304.  In an R-L series circuit the power factor is

A.  leading

B.  lagging

C.  zero

D.  unity

View Answer:

Answer: Option B

Solution:

305.  When a sinusoidal voltage is applied across an R-L series circuit having R = XL, the phase angle will be

A.  90°

B.  45° lagging

C.  45° leading

D.  90° leading

View Answer:

Answer: Option B

Solution:

306.  An  ac  source  having  voltage  e  =  110  sin  (ωt  +  π/3)  is  connected  in  an  ac circuit. If the current drawn from the circuit varies as i = 5 sin (ωt  –  π/3) the impedance of the circuit will be

A.  22 Ω

B.  16 Ω

C.  30.8   Ω

D.  none of these

View Answer:

Answer: Option A

Solution:

307.  Which are of the following true of the circuit shown in the given figure?
MCQ in AC Circuits Part 7 REE Board Exam image for no.307

1.  VR =  100√2  V        2.  I = 2 A      3.  L = 0.25 H

Select the correct answer using the codes given below:

Codes:

A.  2 and 3

B.  1 and 2

C.  1 and 3

D.  1, 2 and 3

View Answer:

Answer: Option A

Solution:

308.  The  R-L  circuit  of  the  figure  is  fed  from  a  constant  magnitude  variable frequency  sinusoidal  voltage  source  vin.  At  100  Hz,  the  R  and  L  element each has a voltage drop Vrms. If the  frequency of the source is changes to 50 Hz, then new voltage drop across R is
MCQ in AC Circuits Part 7 REE Board Exam image for no.308

A.  √(5/8) Vrms

B.  √(2/3) Vrms

C.  √(8/5) Vrms

D.  √(3/2) Vrms

View Answer:

Answer: Option C

Solution:

309. An ac source of 200 Vrms supplies active power of 600 W and reactive power of 800 VAR. The rms current drawn from the source is

A.  10 A

B.  5 A

C.  3.75 A

D.  2.5 A

View Answer:

310.  A square wave is fed to an R-C circuit. Then

A.  voltage across R is square and across C is not square

B.  voltage across C is square and across R is not square

C.  voltage across both R and C is square

D.  voltage across both R and C is not square

View Answer:

Answer: Option D

Solution:

311.  The  voltage  phasor  of  a  circuit  is 10∠15° V  and  the  current  phasor  is 2∠-45° A. The active and reactive powers in the circuit are

A.  10 W and 17.32 VAR

B.  5 W and 8.66 VAR

C.  20 W and 60 VAR

D.  20√2 W and  10√2 VAR

View Answer:

Answer: Option A

Solution:

312.  In a two-element series circuit, the applied voltage and resultant current are respectively, v(t) = 50 + 50 sin (5 x 103 t) and i(t) = 11.2 sin (5 x 103 t + 63.4°). The nature of the elements would be

A.  R-L

B.  R-C

C.  L-C

D.  neither R, nor L, nor C

View Answer:

Answer: Option B

Solution:

313.  A  series  circuit  passive  elements  has  the  following  current  and  applied voltage: v = 200 sin (2,000t + 50°), i = 4 cos (2,000t + 13.2°). The circuit elements

A.  must be resistance and capacitance

B.  must be resistance and inductance

C.  must be inductance, capacitance and resistance

D.  could  be  either  resistance  and  capacitance  or  resistance,  inductance and capacitance

View Answer:

Answer: Option D

Solution:

314.  A two terminal black box contains one of the R-L-C elements. The black box is connected to a 220 V ac supply. The current through the source is I. When a capacitance of 0.1 F is inserted in series between the source and the box, the current through the source is 2I. The element is

A.  a resistance

B.  an inductance

C.  a capacitance

D.  it is not possible to determine the element

View Answer:

Answer: Option B

Solution:

315.  In the following circuit, i(t) under steady state is
MCQ in AC Circuits Part 7 | REE Board Exam

A.  zero

B.  5

C.  7.07 sin t

D.  7.07 sin (t – 45°)

View Answer:

Answer: Option D

Solution:

316.  The source in the circuit is a sinusoidal source. The supply voltages across various elements are marked in the figure. The input voltage is
MCQ in AC Circuits Part 7 | REE Board Exam

A.  10 V

B.  5 V

C.  27 V

D.  24 V

View Answer:

Answer: Option B

Solution:

317.  In the circuit shown in the given figure, if the power consumed by the 5 Ω resistor is 10 W, then the pf of the circuit is
MCQ in AC Circuits Part 7 | REE Board Exam

A.  0.8

B.  0.6

C.  0.5

D.  zero

View Answer:

Answer: Option B

Solution:

318.  In  an  RL  circuit,  supplied  from  an  ac  source,  the  reactive  power  is proportional to the

A.  the average energy stored in the electric field

B.  the average energy stored in the magnetic field

C.  sum of the average energy stored in the electric field and that stored in the magnetic field

D.  difference  of  the  average  energy  stored  in  the  electric  field  and  that stored in the magnetic field

View Answer:

Answer: Option D

Solution:

319.  If a series RLC circuit excited by a voltage e = E sin ωt when LC < 1/ω2

A.  current lags behind the applied voltage

B.  current leads the applied voltage

C.  current is in phase with the applied voltage

D.  voltage across L and C are equal

View Answer:

Answer: Option B

Solution:

320.  The current in the circuit shown is
MCQ in AC Circuits Part 7 | REE Board Exam

A.  5 A

B.  10 A

C.  15 A

D.  25 A

View Answer:

Answer: Option A

Solution:

321.  In the case of the R-L-C circuit shown in the given figure, the voltage across the R, L and C would be respectively
MCQ in AC Circuits Part 7 REE Board Exam image for no.321

A.  12 V, 16 V and 7 V or 25 V

B.  16 V, 12 V and 7 V or 25 V

C.  7 V, 16 V and 12 V

D.  16 V, 12 V and 25 V

View Answer:

Answer: Option A

Solution:

322.  Consider the following statements regarding the circuit shown in the figure.
MCQ in AC Circuits Part 7 | REE Board Exam

If the power consumed by 5 Ω resistor is 10 W then

1.  |I| = √2  A

2.  the total impedance of the circuit is 5 Ω

3.  cos θ = 0.866

Which of these statements is correct?

A.  1 and 3

B.  2 and 3

C.  1 and 2

D.  1, 2 and 3

View Answer:

Answer: Option A

Solution:

323.  In an ac circuit if voltage V = (a + jb) and current I = (c + jd), then the power is given by

A.  ac + ad

B.  ac + bd

C.  bc – ad

D.  bc + ad

View Answer:

Answer: Option B

Solution:

324.  The reactive power drawn from the source in the network in the given figure is
MCQ in AC Circuits Part 7 REE Board Exam image for no.324

A.  300 VAR

B.  200 VAR

C.  100 VAR

D.  zero

View Answer:

Answer: Option D

Solution:

325.  A  series  R-L-C  circuit,  consisting  of  R  =  10  Ω,  XL  =  20  Ω,  XC  =  20  Ω  is connected  across  an ac supply  of  100  V  (rms).  The  magnitude  and  phase angle (with reference to supply voltage) of the voltage across the inductive coil are respectively

A.  100 V, 90°

B.  100 V, -90°

C.  200 V, -90°

D.  200 V, 90°

View Answer:

Answer: Option D

Solution:

326.  For a capacitor in a sine wave ac circuit

A.  vC lags iC by 90°

B.  iC leads vC by 90°

C.  iC and vC have the same frequency

D.  all of these

View Answer:

Answer: Option D

Solution:

327.  In a series RC circuit,

A.  VC leads VR by 90°

B.  VC and I are in phase

C.  VC lags VR by 90°

D.  both B and C

View Answer:

Answer: Option C

Solution:

328.  In a series RC circuit,

A.  VC and VR are in phase

B.  VT and I are always in phase

C.  VR and I are in phase

D.  VR leads I by 90°

View Answer:

Answer: Option C

Solution:

329.  When the frequency of the applied voltage increases in a series RC circuit

A.  the phase angle, θT, becomes more negative

B.  ZT increases

C.  ZT decreases

D.  both A and B

View Answer:

Answer: Option C

Solution:

330.  Inductive reactance, XL

A.  applies only to non-sinusoidal waveforms or dc

B.  applies only to sine waves

C.  applies to either sinusoidal or non-sinusoidal waveforms

D.  is inversely proportional to frequency

View Answer:

Answer: Option B

Solution:

331.  For an inductor in a sine wave ac circuit

A.  VT leads iL by 90°

B.  VT lags iL by 90°

C.  VT and iL are in phase

D.  none of these

View Answer:

Answer: Option A

Solution:

332.  In a series RL circuit,

A.  VT lags VR by 90°

B.  VT leads VR by 90°

C.  VR and I are in phase

D.  both B and C

View Answer:

Answer: Option D

Solution:

333.  In a series RL circuit where XL = R, the phase angle, θZ, is

A.  -45°

B.  0°

C.  90°

D.  45°

View Answer:

Answer: Option D

Solution:
In a series RL circuit where the inductive reactance (XL) is equal to the resistance (R), it implies that the phase angle between the voltage and the current is 45 degrees, as the impedance (Z) is purely resistive. Therefore, the correct answer is:

D. 45°

334.  In an ac circuit with only series resistances

A.  VT and I are in phase

B.  RT =R1 + R2 + R3 + … + etc.

C.  each voltage drop is in phase with the series current

D.  all of these

View Answer:

Answer: Option D

Solution:

335.  The unit of apparent power is the

A.  volt-ampere (VA)

B.  watt (W)

C.  volt-ampere-reactive (VAR)

D.  joule (J)

View Answer:

Answer: Option A

Solution:

336.  In an ac circuit with only series capacitors

A.  VT leads I by 90°

B.  VT lags I by 90°

C.  each capacitor voltage drop leads I by 90°

D.  both A and C

View Answer:

Answer: Option B

Solution:

337.  The unit of real power is the

A.  watt (W)

B.  volt-ampere (VA)

C.  joule (J)

D.  volt-ampere-reactive (VAR)

View Answer:

Answer: Option A

Solution:

338.  In a series RLC circuit

A.  XL and XC are 180° out of phase

B.  IL and IC are 180° out of phase

C.  XL and XC are 90° out of phase

D.  XL and XC are in phase

View Answer:

Answer: Option A

Solution:

339.  The power factor of an ordinary electric bulb is

A.  zero

B.  unity

C.  slightly more than unity

D.  slightly less than unity

View Answer:

Answer: Option B

Solution:

340.  The power factor of an ac circuit is equal to

A.  cosine of the phase angle

B.  sine of the phase angle

C.  unity for a resistive circuit

D.  unity for a reactive circuit

View Answer:

Answer: Option A

Solution:

341.  If f(t) = sin t + sin √2 t is passing through R = 1 ohm, what is the power dissipated in 1 ohm resistor?

A.  1 W

B.  2 W

C.  since f(t) in non-periodic, not possible to find power

D.  none of these

View Answer:

Answer: Option A

Solution:

C.  PARALLEL CIRCUITS

342.  EE Board Exam October 1981

A circuit consists of XL = j5 ohms, XC = -j5 ohms and R = 5 ohms all are connected in parallel. Find the equivalent impedance.

A.  5.5 Ω

B.  5.0 Ω

C.  4.8 Ω

D.  5.2 Ω

View Answer:

Answer: Option B

Solution:

Solution: Find the equivalent impedance

343.  EE Board Exam October 1985

Given: Z1  =  -j2.5 ohms; Z2  = j4 ohms; Z3  = 5 ohms; Z = 1 + j5 ohms. If the four impedances are connected in parallel, find the equivalent impedance in ohms.

A.  4.1 + j0.72

B.  4.3 + j0.45

C.  4.2 + j0.35

D.  4.0 + j0.97

View Answer:

Answer: Option A

Solution:

344.  EE Board Exam April 1984, April 1987

Three impedances Za = 3 + j4 ohms, Zb = 4 –  j4 ohms  and Zc = j3 ohms are connected in parallel. Solve for the pf of the combination.

A.  0.653 leading

B.  0.554 lagging

C.  0.503 leading

D.  0.620 lagging

View Answer:

Answer: Option B

Solution:

345.  EE Board Exam October 1993

A pure capacitance of 530.515 x 10-6 farad and an inductance of 530.515 x 10-4 Henry  are  connected  in parallel  across  an ac  power  source.  Solve  for the resultant impedance assuming that the frequency is 30 Hz.

A.  10 Ω

B.  infinite

C.  zero

D.  undefined

View Answer:

Answer: Option B

Solution:

346.  REE Board Exam March 1998

A coil of a 50-ohm resistance and of 150 mH inductance is connected in parallel with a 50 μF capacitor. What is the power factor of the circuit?

A.  80%

B.  50%

C.  70%

D.  60%

View Answer:

347.  EE Board Exam April 1982

Three impedances Za, Zb and Zc are connected in parallel. If at 60 Hz, Za = j8, Zb = -j2 and Zc = 5 ohms. Solve for the resultant power factor.

A.  0.471 lagging

B.  0.471 leading

C.  0.573 lagging

D.  0.573 leading

View Answer:

Answer: Option B

Solution:

348.  REE Board Exam October 1997

A resistor of 50 ohms and an impedance of 100 + j50 ohms are connected in parallel across a 220 volts supply. What is the power factor of the load?

A.  96%

B.  99%

C.  98%

D.  95%

View Answer:

349.  EE Board Exam October 1992

A capacitor of 3.18 microfarads is connected in parallel with a resistance of 2,000  ohms.  The  combination  is  further  connected  in  series  with  an inductance of 795 mH and  resistance of 100 ohms across a supply given by e = 400 sin wt + 80 sin (3wt + 60°). Assume w = 314 radians/sec. Determine the power dissipated.

A.  74.66 W

B.  78.05 W

C.  80.28 W

D.  75.66 W

View Answer:

Answer: Option A

Solution:

350.  EE Board Exam October 1992

A capacitor of 3.18 microfarads is  connected in parallel with a resistance of 2,000  ohms.  The  combination  is  further  connected  in  series  with  an inductance of 795 mH and resistance of 100 ohms across a supply given by e = 400 sin wt + 80 sin (3wt + 60°). Assume w = 314 radians/sec. Determine the circuit power factor.

A.  0.702

B.  0.650

C.  0.633

D.  0.612

View Answer:

Answer: Option B

Solution:

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