Question

Three objects colored black, gray and white can with stand hostile conditions upto ${2800}^{o}C$. These objects are thrown into furnace where each of them attains a temperature of ${2000}^{o}C$, Which object will glow brightest

• A. the white object
• B. the black object
• C. all glow with equal brightness
• D. gray object

Answer 1

Answer: (B)

the black object

Black has greatest emissivity and greatest absorptivity as compared with other colours. At ${2000}^{o}C$ it will have greatest emissivity so it will glow brightest.