The temperature of a radiating surface changes from 400 K to 1200 K. The ratio of total emissive powers at the higher and lower temperatures would be-

Question

Question

This question was previously asked in

NPCIL SA/ST ME GJ Held on 08/11/2019, Shift-1

Answer 1

Concept:

Stefan-Boltzmann Law

The thermal energy radiated by a black body per second per unit area is proportional to the fourth power of the absolute temperature and is given by:

E ∝ T4

E = σT4

σ = The Stefan – Boltzmann constant = 5.67 × 10-8 W m-2K-4

Calculation:

Given:

T₁ = 400 K, T₂ = 1200 K