Current in an alternating circuit is ahead of voltage by a phase difference of π/3 . The alternating circuit is

RC circuit

The correct answer is option (1) : RC circuit

In alternating current circuits, the phase relationship between current and voltage depends on the components present in the circuit.

• In a pure resistive circuit, current and voltage are in phase (phase difference = 0).

• In a pure capacitive circuit, current leads voltage by π/2.

• In a pure inductive circuit, current lags voltage by π/2.

• In an LC circuit, the phase difference is either 0 at resonance or depends on the net reactance, but it is not π/3.

However, in circuits that contain both resistance and reactance (such as RC or LR circuits), the phase difference can take any value between 0 and π/2.

In an RC circuit, the current leads the voltage, and the phase angle is given by

tan φ = Xᶜ / R

Thus the phase angle can lie in the range

0 < φ < π/2

Since π/3 (60°) lies within this range, such a phase difference is possible in an RC circuit.

Checking the other options:

• LC circuit: current and voltage are either in phase at resonance or determined by net reactance, but not specifically π/3.

• LR circuit: current lags voltage, not ahead.

• L circuit: current lags voltage by π/2.

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