1. The main advantage of alternating current (AC) over direct current (DC) is that:
Answer:
Explanation:
Transformers work on the principle of electromagnetic induction, which is only possible with AC.
2. The frequency of the domestic power supply in most countries is:
Answer:
Explanation:
Most countries, especially in Europe and Asia, use a 50 Hz frequency for their domestic power supply.
3. In an AC circuit, the value which represents its maximum voltage is called:
Answer:
Explanation:
Peak voltage represents the maximum voltage value in an AC circuit.
4. Which of the following devices works on the principle of mutual induction?
Answer:
Explanation:
Transformers work based on the principle of mutual induction between two or more coils.
5. The current which changes its direction periodically is:
Answer:
Explanation:
Alternating Current (AC) changes its direction and magnitude periodically.
6. In a purely resistive AC circuit, the current:
Answer:
Explanation:
In a purely resistive circuit, voltage and current are in phase with each other.
7. In a purely capacitive AC circuit, the current:
Answer:
Explanation:
In a purely capacitive circuit, current leads the voltage by 90°.
8. The power factor of a purely resistive AC circuit is:
Answer:
Explanation:
Power factor is the cosine of the phase angle. For a purely resistive circuit, the phase angle is 0°, making the power factor 1.
9. The impedance of an AC circuit is the:
Answer:
Explanation:
Impedance combines both resistance and reactance, offering total opposition to AC.
10. A choke is used in a tube light to:
Answer:
Explanation:
The choke, being an inductor, provides a large inductive reactance that momentarily increases the voltage to start the discharge in the tube.
11. The reactance offered by a capacitor to alternating current is:
Answer:
Explanation:
Capacitive reactance, Xc = 1/(2πfC), where f is frequency and C is capacitance.
12. Which device converts AC into DC?
Answer:
Explanation:
A rectifier is an electrical device that converts alternating current (AC) to direct current (DC).
13. The power consumed in a purely capacitive circuit is:
Answer:
Explanation:
In a purely capacitive circuit, the power factor is zero, hence power consumed is zero.
14. The symbol '~' represents:
Answer:
Explanation:
The '~' symbol is used to represent alternating current (AC).
15. In a series LCR circuit at resonance, the:
Answer:
Explanation:
At resonance in a series LCR circuit, the inductive reactance equals capacitive reactance, making impedance minimum and current maximum.