Question

As a body is heated to a very high temperature and becomes self-luminous, the apparent color of the emitted radiation shifts from red to yellow and finally to blue as the temperature increases. Why does the color shift? What other changes in the character of the radiation occur?

Short answer

As a body is heated to a very high temperature, wavelength of emitted light decreases which causes the color shifting. Brightness of the radiation will keep on increases.

Step-by-step solution

State Wien displacement law

Wien displacement law states when a body is heated and emits radiation then peak wavelength at which emitted intensity per wavelength interval is largest, is inversely proportional to temperature of the body. This law is based on experiments.

Apply the law for given phenomena

As a body is heated to a very high temperature and becomes self-luminous, the apparent color of the emitted radiation shifts from red to yellow and finally to blue as the temperature increases.

When body is heated so its temperature keep on rising which lead to shorter peak wavelengths of emitted radiation as per Wien displacement law.

The decreasing order of wavelength for visible colors is; $\mathrm{Red}>\mathrm{Yellow}>\mathrm{Blue}$.

Thus, as a body is heated to a very high temperature, wavelength of emitted light decreases which causes the color shifting. Brightness of the radiation will keep on increases.