# Test and Measurement World

## Test and Measurement World Terminology Section

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## Period vs Frequency | Difference between period and Frequency

This page compares period vs frequency and mentions difference between period and frequency. It mentions frequency definition and meaning and period definition and meaning with equation. It mentions calculators to convert period vs frequency and viceversa.

Many alternating voltages and currents produced by them change periodically with respect to time. This means, the V or I waveforms have regular periodic patterns. In this pattern, waveforms repeat over and over as time proceeds. Here one complete alternation is known as 'cycle'.

### Frequency definition or Meaning Frequency definition: The number of cycles occurring in a period of one second is known as frequency of the waveform (voltage or current). The frequency is measured in unit called as 'Hertz' or abbreviated as 'Hz'. Earlier frequency was measured in cycles/second.

The figure depicts 3 cycles of sine wave. Hence value of frequency is equal to 3 Hz. In most of the countries frequency of mains AC supply is 50 Hz. This means waveform is repeated 50 times in time period of about 1 second.

### Period definition or meaning

Period definition : The time for which one cycle will last is known as period of the A.C.
Both the period and frequency are related as per following equation.
Time Period = 1/Frequency
For 50 Hz frequency, period is equal to 1/50 or 0.02 second

Amplitude or peak value of alternating quantity is either its maximum or minimum value. There are different designations for frequencies having different values or range. Alternating currents with frequencies from 20 Hz to 20,000 Hz is known as audio frequency currents. Alternating currents having frequencies above 20 KHz (i.e. 20,000 Hz) is known as radio frequency currents.

There are other units of frequency which are easy to remember when it is in large value, for example KHz (i.e. Kilohertz), MHz (i.e. Megahertz) and GHz (i.e. Gigahertz) .
1 KHz = 10 3 Hz ,
1 MHz = 10 6 Hz and
1 GHz = 109 Hz

### Period vs frequency conversion calculators

Following calculators help in conversion between period vs frequency and viceversa. Following calculator-1 converts period to frequency.

#### Period to frequency conversion

Period, ms (input):

Frequency, Hz (Output):

Example#1:
INPUTS : Period = 2 ms
OUTPUTS: Frequency = 500 Hz

#### Frequency to period conversion

Following calculator-2 converts frequency to period.

Frequency, Hz (input):

Period, ms (Output):

Example#2:
INPUTS : Frequency = 1000 Hz
OUTPUTS: Period = 1 ms