Question

The emissivity of radiation is between__________

(a) 0 and 1

(b) 0 and 10

(c) 0 and 15

(d) 0 and 11

The question was asked during a job interview.

This intriguing question originated from Heat Radiation topic in division Heat Transfer Theory of Food Processing Unit Operations

Answer 1

Right option is (a) 0 and 1

The explanation is: The emissivity of radiation is between0 and 1. It can be defined as the ratio of the thermal radiation from the surface to the radiation from an ideal black surface at a constant temperature. This is derived under Stefan–Boltzmann law.