The AC mains domestic supply current in India changes direction in every

In India, the domestic alternating current (AC) supply has a standard frequency of 50 Hz, which means it completes 50 cycles per second. Each cycle consists of two halves: a positive half-cycle and a negative half-cycle.

• Time Period (T): The time taken to complete one full cycle is the reciprocal of the frequency (1/f). For a 50 Hz supply, T = 1/50 seconds.
• Direction Change: The current changes its direction at the end of every half-cycle. Since one full cycle takes 1/50 seconds, a half-cycle takes exactly half of that time.
• Calculation: (1/50) ÷ 2 = 1/100 seconds.

Consequently, the current reverses its direction every 1/100 second. This explains why Option D is the correct answer.