An iron plate at with emissivity radiates power per unit area

PHYSICS · Subjective · AP · Physics 2: Algebra-based · Modern Physics · Modern Physics

Problem

An iron plate at

700\,\text{K}

with emissivity

0.6

radiates power

P

per unit area. The plate is coated with lamp-black paint, increasing its emissivity to

0.9

, and is simultaneously cooled to

600\,\text{K}

. Determine the new power per unit area as a fraction of

P