Circuits And Circuit Theory(Electrical Engineering > A.c Fundamentals ) Questions and answers for exam Preparation

Question 1. The transient currents are associated with the

Changes in the stored energy in the inductors and capacitors
Impedance of the circuit
Applied voltage to the circuit
Resistance of the circuit

Explanation:-

Answer: Option A. -> Changes in the stored energy in the inductors and capacitors

Question 2. In any A.C. circuit always

Apparent power is more than actual power
Reactive power is more than apparent power
Actual power is more than reactive power
Reactive power is more than actual power

Explanation:-

Answer: Option A. -> Apparent power is more than actual power

Question 3. The inductance of a coil can be increased by

Increasing core length
Decreasing the number of turns
Decreasing the diameter of the former
Choosing core material having high relative permeability

Explanation:-

Answer: Option D. -> Choosing core material having high relative permeability

Question 4. Which of the following refers to a parallel circuit?

The current through each element is same
The voltage across element is in proportion to it's resistance value
The equivalent resistance is greater than any one of the resistors
The current through any one element is less than the source current

Explanation:-

Answer: Option D. -> The current through any one element is less than the source current

Question 5. Power factor of an electrical circuit is equal to

$$\frac{{\text{R}}}{{\text{Z}}}$$
Cosine of phase angle difference between current and voltage
Ratio of useful current to total current $$\frac{{I{\text{w}}}}{l}$$
All above

Explanation:-

Answer: Option D. -> All above

Question 6. The peak value of a sine wave is 200 V. Its average value is

127.4 V
141.4 V
282.8 V
200 V

Explanation:-

Answer: Option A. -> 127.4 V

Question 7. The product of apparent power and cosine of the phase angle between circuit voltage and current is

True power
Reactive power
Volt-amperes
Instantaneous power

Explanation:-

Answer: Option A. -> True power

Question 8. Which of the following waves has the highest value of peak factor ?

Square wave
Sine wave
Half wave rectified sine wave
Triangular wave

Explanation:-

Answer: Option C. -> Half wave rectified sine wave

Question 9. Pure inductive circuit takes power from the A.C. line when

Applied voltage decreases but current increases
Applied voltage increases but current decreases
Both applied voltage and current increase
Both applied voltage and current decrease

Explanation:-

Answer: Option A. -> Applied voltage decreases but current increases

Question 10. In a purely inductive circuit

Actual power is zero
Reactive power is zero
Apparent power is zero
None of above is zero

Explanation:-

Answer: Option A. -> Actual power is zero