Question

What is the value of emissivity for polished copper?

(a) 0.02

(b) 0.03

(c) 0.04

(d) 0.05

This question was addressed to me in an interview.

My question comes from Emissivity topic in chapter Modes and Diffusion of Mass Transfer

Answer 1

The correct option is (b) 0.03

For explanation I would say: This is the total hemispherical emissivity from the surfaces. It describes thermal radiation emitted near specific wavelength and at specific angles to surface.