What formula is used to calculate frequency in an AC circuit?

The formula for calculating frequency in an AC circuit is f = 1/T, where 'f' represents frequency in hertz (Hz) and 'T' denotes the period in seconds (s). This equation indicates that frequency is the reciprocal of the period; as the time taken for one complete cycle (the period) decreases, the frequency increases, and vice versa.

In practical terms, if you know the time it takes for one complete cycle of the waveform (the period), you can easily determine how many cycles occur in one second (the frequency) by simply taking the reciprocal. This relationship is fundamental in understanding alternating current circuits, as frequency is a key parameter influencing how electrical devices operate.

The other formulas provided relate to different aspects of electrical circuits but do not correctly convey the relationship between frequency and period. For example, the notion that frequency could be derived from voltage and current or through multiplication by a factor does not address the fundamental definition of frequency in terms of time.