Question

Explain Radiation.

Answer 1

1. Heat transfer that takes place between 2 bodies in the absence of a medium between them through waves or particles is called radiation
2. If heat transfer takes place through electromagnetic waves formed by the superposition of electric and magnetic fields perpendicular to each other, it is called electromagnetic radiation
3. Examples of electromagnetic radiation include radio waves used for communication, microwaves,x-rays, gamma rays, etc
4. The electromagnetic waves travel at the speed of light and the relation between frequency and wavelength is given by $c=\lambda v$ where c is the speed of light, $\lambda$ is the wavelength, and $v$ is the frequency of the wave
5. The diagram below shows the electromagnetic spectrum

Other types of radiation,

1. Particle radiation includes the emission of particles like alpha ( $\alpha$)-particle, beta particle, etc
2. Acoustic radiation is through sound waves like ultrasound or seismic waves. these waves require medium
3. Gravitational radiation includes the formation of gravitational waves or ripples in the space-time fabric.