Hertz is the unit of frequency. Frequency refers to the number of repetitions of 1 second when electric pulse, alternating current waveform, electromagnetic wave, sound wave and mechanical vibration circulate. 1Hz stands for vibration per second 1 cycle, and 60Hz stands for vibration of 60 cycles per second.

For sound, people's hearing range is 20 Hz ~ 20Hz~20000Hz, below which it is called infrasound, and above which it is called ultrasound.

Produce history

Heinrich? Rudolph? German physicist Hertz (1857~ 1894) first proved the existence of electromagnetic waves by experiments in 1887, and published a paper in 1888. He made great contributions to electromagnetism, so the international unit of frequency Hertz was named after him.

Electricity (voltage or current) can be divided into DC and AC. In communication applications, alternating current is usually used for signal transmission.

Hertz experiment proves that electromagnetic wave exists, and its propagation speed is equivalent to the speed of light. Hertz experiment has opened up an innovative road for the development of radio electronic technologies such as radio, radar and television. He studied the influence of ultraviolet light on spark discharge and found photoelectric effect from it. He thought that an object can release electrons under the irradiation of light, and this discovery became the basis for Einstein to establish the quantum theory of light.

Refer to the above? Baidu encyclopedia-hertz