Electrical Engineering Exam Practice MCQ Test 1: AC Fundamentals

By examgeniushub.com / December 15, 2024

Welcome to the Electrical Engineering Exam Practice MCQ Test 1 focusing on AC Fundamentals! This test is designed to help students strengthen their understanding of key concepts in Alternating Current (AC) theory, a crucial topic in electrical engineering. Whether you’re preparing for competitive exams like GATE, GPSC, or university-level assessments, this test will provide valuable practice.

About the Test

Total Questions: 25 Multiple Choice Questions (MCQs)
Topics Covered:
1. Basic AC Concepts: Frequency, time period, and sine wave characteristics
2. Root Mean Square (RMS) and Peak Values
3. Reactance: Inductive and Capacitive
4. Impedance and Phasor Diagrams
5. Power in AC Circuits: Real, Reactive, and Apparent Power
6. Resonance in RLC Circuits

Results

#1. A standard sinusoidal voltage wave changes its polarity at________

maximum value

minimum value

zero value

none of the above

#2. The period of a certain sine wave is 10 milliseconds. Its frequency is________

10 MHz

10 KHz

10 Hz

100 Hz

#3. Two sine waves are said to be in phase with each other if they achieve their______

zero value at the same time

maximum value at the time

minimum value at the same time

all of the above

#4. The average value of a sine wave of maximum value Im over one cycle is_______

Im/π

2Im/π

zero

Im/2

#5. The rms value of a sine wave of maximum value 10A equals a dc current of ______ampere.

7.07

6.37

5.77

#6. The rms value of a sinusoidal voltage with peak-to-peak value of 240 V is________V.

84.84

77.82

94.68

89.15

#7. The distance occupied by one complete cycle of the wave is called its________

time period

wavelength

velocity

frequency

#8. The time period of a sinusoidal waveform with 200 Hz frequency is________second.

0.05

0.005

0.0005

.0.5

#9. The rms value of a sine wave of peak value Im is given by_______

Im/√2

Im/2

Im/π

#10. The peak value of a sine wave is 400 V. Its average value is_________

254.6 V

282.6 V

400 V

565.5 V

#11. The form factor of a sine wave is_____

1.01

1.11

1.21

none of the above

#12. An alternating current is given by the expression 𝑖 = 200 sin (314𝑡 + 𝜋/3 ) amperes. The maximum value and frequency of the current are_________

200 A, 50 Hz

100√2, 50 Hz

200 A, 100 Hz

200 A, 25 Hz

#13. An alternating current of 50 Hz frequency and 100 A maximum value is given by______

𝑖 = 200 𝑠𝑖𝑛628𝑡

𝑖 = 100 𝑠𝑖𝑛314𝑡

𝑖 = 100√2 𝑠𝑖𝑛314𝑡

𝑖 = 100√2 𝑠𝑖𝑛157𝑡

#14. The average value of the current 𝑖 = 200 sin 𝑡 from 𝑡 = 0 to 𝑡 = 𝜋 /2 is ______

400 π

400 / 𝜋

1/400

𝜋/400

#15. An alternating current of 50 Hz frequency has a maximum value of 100 A. Its value 1/600 second after the instant current is zero will be________

25 A

12.5 A

50 A

75 A

#16. When two quantities are in quadrature, the phase angles between them will be________

45°

90°

135°

60°

#17. The alternating voltage 𝑒 = 200 sin 314𝑡 is applied to a device which offers an ohmic resistance of 20 Ω to the flow of current in one direction while entirely preventing the flow in the opposite direction. The average value of the current will be_________

5 A

3.18 A

1.57 A

1.10 A

#18. The ac system is preferred to dc system because_______

ac voltages can be easily changed in magnitude

dc motors do not have fine speed control

high voltage ac transmission is less efficient

dc voltage can not be used for domestic appliances

#19. A sine wave has a maximum value of 20 V. Its value at 135° is______

10 V

14.14 V

15 V

5 V

#20. In ac system, we generate sine waveform because_______

it can be easily drawn

it produces least disturbance in electrical circuits

it is nature’s standard

other waves can not be produced easily

#21. An alternating voltage is given by 𝑣 = 30 𝑠𝑖𝑛314𝑡 .The time taken by the voltage to reach 30 V for the first time is_____

0.02 second

0.1 second

0.03 second

0.005 second

#22. __________will work only on dc supply

electric lamp

electroplating

refrigerator

heater

#23. A sinusoidal current has a magnitude of 3 A at 120°. Its maximum value will be_____

√3 A

√3/ 2 A

2√3 A

6 A

#24. An alternating voltage is given by 𝑣 = 20 sin 157𝑡. The frequency of the alternating voltage is_____

50 Hz

25 Hz