Answer: A black body is a physics idealisation of a body that absorbs all incident electromagnetic radiation, regardless of frequency or angle.
An ideal black substance in thermal equilibrium has the following two characteristics:
- Ideal emitter: The body emits more thermal radiation energy than any other body at any frequency and at any temperature.
- Spreading emitter A unit area perpendicular to the direction is used to measure this.
- When light enters the cavity through the hole of the black body when it strikes the cavity, no light is reflected from the cavity.