Question

The minimum temperature of a body at which it emits light is

• A. ${1200}^{o}C$
• B. ${1000}^{o}C$
• C. ${500}^{o}C$
• D. ${200}^{o}C$

Answer 1

The correct option is C ${500}^{o}C$

A black body in thermal equilibrium (that is, at a constant temperature) emits electromagnetic black-body radiation. From the Spectrum Plot of a blackbody with different temperatures, we can conclude that as the temperature increases past about $500{}^{\circ }C$, black bodies start to emit significant amounts of visible light viewed in the dark by the human eye.