**Definition:**

The frequency is the variety of oscillation per unit time. It is used for defining the cyclic process like rotation, oscillation, wave and so on. Frequency is the numbers of cycles in in an ac sine wave. Frequency is the rate at which current changes direction per seconds.

The SI unit of the frequency is hertz.

Cycle = one whole wave of alternating cutting-edge or voltage.

Alternation = one half of a cycle.

Length = the time required to produce one complete cycle of a waveform.

At its maximum fundamental, frequency is how frequently some thing repeats. Inside the case of electrical contemporary, frequency is the number of instances a sine wave repeats, or completes, a positive to negative cycle.

The greater cycles that arise in line with 2d, the better the frequency.

The image λ represents it. The only hertz means the wave finished one cycle in a single 2d. The conventional unit for measuring the cyclic method is revolution in keeping with second that’s equal to at least one hertz.

The frequency is the parameter which explains the phenomenon of oscillatory and vibration just like the mechanical vibration, sound alerts, light, frequency waves and so forth. The time period “duration” represents the time required through the wave for one oscillation, i.E., it’s miles inversely proportional to the frequency.

Frequency is the total number of oscillations in step with unit time. If we take the example of the flashes, then the length is the time among the two flashes. And the frequency is the total number of flashes in keeping with second.

**Types of frequency:**

The frequency is particularly classified into two classes.

**1. Angular frequency **–

The angular frequency shows the wide variety of revolution on the fixed c language of time. The unit of angular frequency is hertz. The relation between the frequency and angular frequency is expressed as;

In which, ω – angular frequency

**2. Spatial frequency – **

the frequency which relies upon on the spatial coordinate is known as the spatial frequency. It’s miles inversely proportional to the wavelength. The spatial frequency measures the characteristic of the structure this is periodic in space.

**How to measure frequncy:**

A virtual multimeter that includes a frequency counter mode can degree the frequency of ac alerts and might additionally provide the subsequent:

min/max recording, which allows frequency measurements to be recorded over a designated period or the identical way voltage, current or resistance measurements are recorded.

Auto-variety, which robotically selects the frequency range, except when the measured voltage is outside the frequency size variety.

Energy grids vary via state. Within the us, the grid is based on a incredibly solid 60-hertz signal, meaning it cycles 60 times in line with second.

Within the us, family electric electricity is primarily based on a single-section, a hundred and twenty-volt ac strength deliver. Strength measured at a wall outlet in a us domestic will yield sine waves that oscillate among ±one hundred seventy volts, with the genuine-rms voltage measuring at one hundred twenty volts. The charge of oscillation could be 60 cycles in line with 2d.

Hertz is called after german physicist heinrich hertz (1857-1894), first to broadcast and receive radio waves. Radio waves travel at one cycle per second(1 hz).

**Some frequency ranges:**

- Electricity line frequency (usually 50 hz or 60 hz).
- Variable-frequency drives, which usually use a 1-20 kilohertz (khz) service frequency.
- Audio frequency range: 15 hz to 20 khz (the variety of human hearing).
- Radio frequency: 30-300 khz.
- Low frequency: three hundred khz to three megahertz (mhz).
- Medium frequency: three-30 mhz.
- High frequency: 30-300 mhz.