Learn How to Calculate Radiation Energy - Tutorial

Definition:

Stefan Boltzmann Law is also known as Stefan's Law. It helps to resolve the unknown quantity between radiation emitted by the body, temperature and the surface area. This law illustrates that, the energy radiated by a blackbody radiator per second per unit area is proportional to the fourth power of the absolute temperature power radiated from a black body in terms of its temperature.

Example:

A Metal ball 3 cm in radius is heated in a furnace to 5000C. If its emissivity is 0.5, at what rate does it radiate energy?

Given,

Radius (r) = 3 cm Temperature (T) = 500⁰C Emissivity (ε) = 0.5

To Find,

Radiation Energy (P)

Solution:

Step1:

First, calculate the Surface area of the ball (A), A = 4 π r² = (4 x 3.142)(0.03 m)² = (12.568) (0.03 m) ² = 0.0113112 m²

Step2:

Now, calculate the Temperature (T), T = 500 ⁰C + 273 T = 773 K.

Step3:

Finally, calculate the Radiation energy (P), P = ε σ A T⁴ P = 0.5 x 5.67 x 10^-8 x 0.0113112 x (773)⁴ P = 114.37 W.