How many times per second does voltage and current change amplitude and direction in a 60-cycle AC circuit?

How many times per second does voltage and current change amplitude and direction in a 60-cycle AC circuit?

• A. 60
• B. 90
• C. 120
• D. 240

Answer: (C)

In a 60-cycle alternating current (AC) circuit, the frequency of the voltage and current is 60 hertz (Hz), which means that the waveform completes one full cycle 60 times every second. Since an AC waveform changes direction twice during each complete cycle—once when it goes from positive to negative and again when it returns to positive—the voltage and current change their amplitude and direction a total of 120 times per second. Therefore, the correct answer is the option that reflects this doubling of occurrences per cycle. In a 60-cycle AC circuit, the voltage and current alternate polarity and reach their peak amplitudes a total of 120 times in one second. This fundamental characteristic of AC power is crucial for understanding how AC systems operate compared to direct current (DC) systems, where direction does not change.

In a 60-cycle alternating current (AC) circuit, the frequency of the voltage and current is 60 hertz (Hz), which means that the waveform completes one full cycle 60 times every second. Since an AC waveform changes direction twice during each complete cycle—once when it goes from positive to negative and again when it returns to positive—the voltage and current change their amplitude and direction a total of 120 times per second.

Therefore, the correct answer is the option that reflects this doubling of occurrences per cycle. In a 60-cycle AC circuit, the voltage and current alternate polarity and reach their peak amplitudes a total of 120 times in one second. This fundamental characteristic of AC power is crucial for understanding how AC systems operate compared to direct current (DC) systems, where direction does not change.