Question

Assertion : No power loss associated with pure capacitor in ac circuit.
Reason: No current is flowing in this circuit.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

Assertion is true. When a capacitor is connected to an a.c. circuit, ${\epsilon }_{rms}=i_{rms}\left(\frac{1}{C\omega }\right)$ where $\frac{1}{C\omega }$ is the impedance due to capacitative resistance. The power consumed in this circuit is zero because the phase difference $\varphi$ between emf and current in a pure capacitance a.c. circuit is $\frac{\pi }{2}.$ Power factor cos $\varphi =0.$ It is only for d.c. that a current does not flow. Reason is false.