In a purely inductive circuit, the current waveform lags the voltage waveform by what angle?

In a purely inductive circuit, the current waveform lags the voltage waveform by what angle?

• A. 0°
• B. 45°
• C. 90°
• D. 180°

Answer: (C)

In a purely inductive circuit, the current waveform lags the voltage waveform by 90 degrees. This phenomenon occurs because inductors resist changes in current. When an alternating current (AC) voltage is applied, the inductor generates a magnetic field that opposes the change in current. As voltage reaches its peak value, the current has not yet reached its peak but is at a quarter of its cycle behind, resulting in the 90-degree phase difference. This relationship is fundamental in understanding AC circuits, particularly in phasor analysis, where voltage and current are represented as rotating vectors. The phase shift indicates that even though the inductor allows current to flow, it does not do so instantaneously in response to the applied voltage. Thus, the voltage reaches its maximum value well before the current does, embodying the characteristic of inductance in AC circuits.

In a purely inductive circuit, the current waveform lags the voltage waveform by 90 degrees. This phenomenon occurs because inductors resist changes in current. When an alternating current (AC) voltage is applied, the inductor generates a magnetic field that opposes the change in current. As voltage reaches its peak value, the current has not yet reached its peak but is at a quarter of its cycle behind, resulting in the 90-degree phase difference.

This relationship is fundamental in understanding AC circuits, particularly in phasor analysis, where voltage and current are represented as rotating vectors. The phase shift indicates that even though the inductor allows current to flow, it does not do so instantaneously in response to the applied voltage. Thus, the voltage reaches its maximum value well before the current does, embodying the characteristic of inductance in AC circuits.