MCQ in Electrical Circuit Part 8 | ECE Board Exam

(Last Updated On: April 18, 2018)

This is the Multiples Choice Questions Part 8 of the Series in Electrical Circuit as one of the Electronics Engineering topic. In Preparation for the ECE 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 Electronics Engineering field, Electronics Books, Journals and other Electronics References.

MCQ Topic Outline included in ECE Board Exam Syllabi

• MCQs in AC-DC circuits
• MCQs in Resistors
• MCQs in Inductors
• MCQs in Capacitors

Continue Practice Exam Test Questions Part 8 of the Series

351. The return point in a circuit, where all voltage measurements are referred.

A.  node

B.  junction

C.  ground

D.  loop

352. Mesh analysis is best used together with what circuit law?

A.  KVL

B.  KCL

C.  VDT

D.  CDT

353. Nodal analysis is best used together with

A.  KVL

B.  KCL

C.  VDT

D.  CDT

354. Three 100 Ω resistors are connected in a tee-form (T) network and is set up between a 100 V supply and a load resistor RL. If maximum power transfer is desired,  what should be the resistance of the load resistor RL?

A.  50 Ω

B.  75 Ω

C.  125 Ω

D.  150 Ω

355. Theorem used in simplifying circuit analysis by considering the effect of supply voltages one at a time.

A.  Thevenin’s theorem

B.  Norton’s theorem

C.  Superposition

D.  KVL

356. Three  resistors,  R1  =  60  Ω,  R2  =  80  Ω  and  R3  =  100  are  connected  in  delta.  If  the network is to be transformed into star, what would be the value of the resistor opposite of R2?

A.  25.0 Ω

B.  33.3 Ω

C.  45.0 Ω

D.  56.7 Ω

357. The description of two sine waves that are in step with each other going through their maximum and minimum points at the same time and in the same direction

A.  phased sine wave

B.  sine waves in phase

C.  sine wave in coordination

D.  stepped sine waves

358. Most ac-supplies are in the form of

A.  sine-wave

B.  square-wave

C.  triangular-wave

D.  rectangular-wave

359. Advantage(s) of ac over dc

A.  economically produced

B.  transmission of ac is more efficient

C.  ac voltages can be easily changed

D.  all of the above

360. An ac-voltage has an equation v = 240 sin120πt, its frequency is

A.  60 Hz

B.  90 Hz

C.  120 Hz

D.  240 Hz

361. When can an ac-voltage, v = 120sin120πt reach its first peak?

A.  4.167 μs

B.  8.334 μs

C.  4.167 ms

D.  8.334 ms

362. Calculate the period of an alternating current having an equation of I = 20sin120πt.

A.  4.167 ms

B.  8.33 ms

C.  16.67 ms

D.  33.33 ms

363. The time taken by an alternating voltage, v = 100sin240πt to reach 50V for the first time

A.  358 μs

B.  695 μs

C.  358 ms

D.  695 ms

364. An alternating voltage of sine-wave form has a maximum voltage of 311V.  What is its value at 225°?

A.  110 V

B.  220 V

C.  -220 V

D.  -110 V

365. If an alternating voltage has a magnitude of 10 V at 30°, what is its maximum voltage?

A.  20 V

B.  30 V

C.  40 V

D.  50 V

366. What is the frequency of an alternating current, if it reaches 90° within 4.167 ms?

A.  20 Hz

B.  30 Hz

C.  50 HZ

D.  60 Hz

367. At  what  angle  does  an  alternating  voltage  of  cosine-waveform  reaches  its  negative peak?

A.  45°

B.  90°

C.  135°

D.  180°

368. When comparing rms voltages and average voltages, which of the following statement is true, assuming sine waves?

A.  Either the rms voltage or the average voltage might be larger

B.  The rms voltage is always greater than the average voltage

C.  There  will  always  be  a  very  large  difference  between  the  rms  voltage  and  the average voltage

D.  The average voltage is always greater than the rms voltage

369. What is the average voltage of an alternating voltage, v = 100sin120πt?

A.  31.8 V

B.  63.6 V

C.  70.71 V

D.  0 (zero) V

370. Determine the effective voltage of v = 100sin120πt.

A.  31.80 V

B.  35.35 V

C.  70.71 V

D.  90.00 V

371. What do you mean by root-mean-squared (rms) value?

A.  it is the average value

B.  it is the effective value

C.  it is the value that causes the same heating effect as a dc-voltage

D.  B or C

372. The power dissipated across the resistance in an AC circuit

A.  real power

B.  reactive power

C.  apparent power

D.  true power

373. In AC circuit, resistors will dissipate what power?

A.  reactive

B.  passive

C.  inductive

D.  true

374. In an ac-circuit, if the voltage and current are in phase, the circuit is

A.  resistive

B.  reactive

C.  capacitive

D.  inductive

375. If the current in an ac-circuit leads the voltage by 90°, the circuit is

A.  resistive

B.  capacitive

C.  inductive

D.  purely inductive

376. In a purely inductive circuit the current

A.  leads the voltage by 45°

B.  leads the voltage by 90°

C.  lags the voltage by 90°

D.  lags the voltage by 45°

377. If the current and voltage in an ac-circuit has a phase difference, it would mean the load is

A.  resistive

B.  capacitive

C.  inductive

D.  reactive

378. A resistive and a capacitive load of equal magnitude is connected in series, determine the phase difference between the voltage and the current.

A.  current leads the voltage by 45°

B.  current lags the voltage by 45°

C.  current leads the voltage by 90°

D.  current lags the voltage by 90°

379. The reactance of a 25 mH coil at 500 Hz is which of the following?

A.  785 ohms

B.  785,000 ohms

C.  13 ohms

D.  0.0013 ohms

380. The impedance in the study of electronics is represented by resistance and ________.

A.  inductance and capacitance

B.  inductance

C.  reactance

D.  capacitance

381. A series circuit consists of an 80 mH inductor and a 150 μF capacitor. Calculate the total reactance if it is connected to a 220-volt 60-cycle source.

A.  12.5 Ω inductive

B.  12.5 Ω capacitive

C.  47.8 Ω inductive

D.  47.8 Ω capacitive

382. Ignoring any inductive effects, what is the impedance of RC series capacitor made up of a 56 kilo ohms resistor and a 0.33 μF capacitor at a signal frequency of 450 Hz?

A.  66,730 ohms

B.  57,019 ohms

C.  45,270 ohms

D.  10,730 ohms

383. A  220-volt,  60-Hz  source  is  driving  a  series  RL  circuit.  Determine  the  current  in  the circuit if R = 100 Ω and XL = 100 Ω.

A.  1.10 A (lagging)

B.  1.55 A (lagging)

C.  2.20 A (lagging)

D.  4.40 A (lagging)

384. How many electrical degrees a current will lead the voltage in a series RC load with R = 100 Ω and XC = 50 Ω?

A.  13.28°

B.  26.56°

C.  31.72°

D.  63.44°

385. What will be the current equation in a series RC network if supplied with v = Vmsin120πt source. The circuit has a power factor pf = 0.5?

A.  i = Imaxsin(120πt + 60)

B.  i = Imaxsin(120πt – 60)

C.  i = Imaxsin(120πt + 30)

D.  i = Imaxsin(120πt – 30)

386. The power factor (pf) of a series LC circuit is

A.  0

B.  0.5

C.  0.75

D.  1.0

387. What is the power factor (pf) of a series RL circuit having R = 50Ω and XL = 20Ω?

A.  0.63

B.  0.71

C.  0.81

D.  0.93

388. A 200Ω resistor if connected in series  with a capacitive reactance of 100 will give a total circuit impedance of

A.  173.2 Ω

B.  223.6 Ω

C.  250.6 Ω

D.  300.0 Ω

389. What will happen when the power factor of a circuit is increased?

A.  reactive power increases

B.  active power increases

C.  both active and reactive powers increases

D.  both active and reactive powers decreases

390. A series RL network is supplied with a 200-volt, 60-cycle source. If the voltage across the resistor R is 100 V, what is the voltage across the inductor L?

A.  0 V

B.  100 V

C.  173.2 V

D.  200 V

391. A 6-Ω resistor is connected in series with a capacitive reactance of 8 Ω. If the supply voltage is 200 V, what is the power consumed by the circuit?

A.  2400 W

B.  4000 W

C.  5000 W

D.  6666.67 W

392. A 6-Ω resistor is connected in series with a capacitive reactance of 8 Ω. If the supply voltage is 200 V, what is the circuit current magnitude?

A.  14.28 A

B.  20 A

C.  25 A

D.  33.33 A

393. A 6-Ω resistor is connected in series with a capacitive reactance of 8 Ω. If the supply voltage is 200 V, what is the apparent power of the circuit?

A.  1200 W

B.  2400 W

C.  3200 W

D.  4000 W

394. The apparent power of a series RC network is given to be 4000 W. If R = 6 Ω, and XC = 8 Ω, calculate the true power of the network.

A.  1200 W

B.  2400 W

C.  3200 W

D.  4000 W

395. A series RC circuit has an apparent power of 4000 W. If R = 6 Ω, and XC = 8 Ω, determine the reactive power.

A.  1200 W

B.  2400 W

C.  3200 W

D.  4000 W

396. A network has a true power and a reactive power of 2400 W and 3200 W respectively. What is its apparent power?

A.  800 W

B.  1600 W

C.  4000 W

D.  5600 W

397. What is the total impedance of a series circuit consisting of R = 6 Ω, XC  = 8 Ω, and XL  = 16 Ω?

A.  10 Ω

B.  14 Ω

C.  24.73 Ω

D.  30 Ω

398. What is the significance of connecting loads in parallel?

A.  it makes power consumption less

B.  it provides greater efficiency

C.  it increases the safety factor

D.  it allows independent operations of loads

399. A parallel RL circuit with R = 60 Ω, and XL = 40 Ω has a total impedance of

A.  24.3 Ω

B.  28.3 Ω

C.  33.3 Ω

D.  38.3 Ω

400.  Calculate the total impedance of a parallel RC circuit if R = XC = 50 Ω.

A.  25 @ 45° Ω

B.  25 @ -45° Ω

C.  35.35 @ 45° Ω

D.  35.35 @ -45° Ω

Questions and Answers in Electrical Circuit

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