Question

As a part of the hardening process a thin square steel plate, measuring 10 cm on a side, is heated in a blacksmith’s forge to a temperature of 800 oC. If the emissivity is 0.60, calculate the net rate of radiation of energy into a room whose temperature is 20 oC.

The answer is 897 W. How is the answer worked out?

Answer 1

SOLUTION;

side length of plate is =10 cm = 0.1 m

Both side area A= 2*(0.1)2=2*10-2 m​​​​​2

Emissivity of plate is

And

Let's the heat rate is

We know this formula

The net radiation energy change is = 897 w

Answer = 897 W