Question

Assertion: Phase is negative for a purely capacitive circuit.
Reason: In the capacitive circuit, the current leads the voltage.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect

Answer 1

Hint: We know that an AC circuit has input voltage and current, in the sinusoidal form. Thus there are 3 possible relationships between voltage and current in the circuit. 1. Voltage lags current or current leads voltage, 2. Voltage leads current or current lags voltage and 3. Voltage and current are in the same phase.


Complete step by step answer:
We know that the source of an AC circuit is sinusoidal. Then there is a phase difference between the voltage and current. If the phase difference between the current and voltage is zero, then both are said to be in phase, and if the phase difference is not equal to zero, then both are said to be out of phase.
In a purely capacitive circuit, the voltage and the current in the circuit are out of phase by $90^{\circ}$, the product of the voltage and current, which is the active power of the circuit is either negative or positive. If the average power is taken, then we get $0$. This is because, for one half of the cycle, the voltage and current are positive

Thus, we can say that in a purely capacitive circuit, there is a phase difference of $90^{\circ}$, where current leads voltage.
Hence, we can conclude that the answer is option B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion

Note:
In a purely capacitive circuit, there is some energy which is stored in the capacitor as an electric field in one quarter cycle. In the next quarter, this energy is dissipated to the source again. This process continues till the source supplies to the capacitor. Hence the capacitor does not consume any power.