Electrical frequency is the number of complete cycles of an alternating current (AC) or voltage waveform that occur in one second. It is measured in hertz (Hz), where 1 Hz means one complete cycle per second. For example, a 50 Hz AC supply completes 50 cycles every second, while a 60 Hz supply completes 60 cycles every second. Frequency determines how quickly the AC voltage and current change direction.
In a sinusoidal AC waveform, frequency is closely related to the time period (T), which is the time required to complete one cycle: f = 1/T. Electrical frequency is important in power systems because generators, transformers, motors, lighting equipment, and many electronic devices are designed to operate at a particular frequency. For example, household electricity in Japan is normally supplied at 50 Hz, meaning the AC waveform completes 50 cycles each second.
Interactive Oscilloscope: Frequency Change
Frequency tells us how many complete cycles a sine wave produces every second. When the frequency increases, the waves become closer together and more cycles appear on the oscilloscope. When the frequency decreases, the waves spread apart and fewer cycles appear.
Relationship: f = 1 / T
where f is frequency in hertz (Hz) and T is the period in seconds.