Question

The emissive power of a black body is proportional to - 
1. E ∝ T⁰
2. E ∝ T²
3. E ∝ T⁴
4. E ∝ T⁵

Answer 1

Correct Answer - Option 3 : E ∝ T⁴

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 Wm-2K-4

The emissive power of a body at a given temperature is the amount of energy emitted per unit of time per unit area of the surface for a given wavelength.

It is the energy of thermal radiation emitted in all directions per unit time from each unit area of a surface at any given temperature.

From the above law, it is clear that 

E ∝ T⁴