Question

Photoelectric effect and electromagnetic spectrum in brief with suitable example

Answer 1

Photoelectric effect is the phenomenon of emission of electrons from the surface of certain materials when light waves with particular frequency and sufficient energy fall on them. It was first observed by Heinrich Hertz. Visible light produces photoelectric effect on alkali metals.


Electromagnetic spectrum is the collection of electromagnetic waves arranged from low frequency electromagnetic waves to high frequency electromagnetic waves.
Electromagnetic waves are produced by electric charge that are accelerating. When a magnetic field combines with electric field electromagnetic waves are produced. The electric field and magnetic wave are perpendicular to one another in electromagnetic waves.

Below are the type of electromagnetic waves in electromagnetic spectrum: (from high frequency ---> low frequency)

Gamma rays - it is in the end of the electromagnetic spectrum, with highest frequency but shortest wavelength. Gamma rays are generated by radioactive substances.

X-rays - it is next to Gamma rays with respect to frequency but has longer wavelength. This wavelength can penetrate metal. It was discovered by Wilhelm Conrad Roentgen in 1895.

Ultraviolet - ultraviolet waves or ultraviolet radiation have shorter wavelength compared to visible light. The main source of UV radiation is the sun.

Visible Light- among other electromagnetic waves, this the only electromagnetic wave that is visible to the naked eye. The waves inside the range of visible light are the colors. From red( longest wavelength inside visible light) to violet (shortest wavelength inside visible light).

Infrared - infrared radiation is beyond the red color on the visible length. Bodies on earth radiated infrared radiation.

Microwaves- higher frequency than radio waves. Commonly used in satelite communications.
Radio waves - these are electromagnetic waves that have longest wavelength. Commonly used in radio transmission.