This question was previously asked in

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

- 3
- 9
- 27
- 81

Option 4 : 81

Free

ST 1: Building Materials

1185

20 Questions
20 Marks
20 Mins

__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:__

T_{1} = 400 K, T_{2} = 1200 K

\(\frac{{{E_2}}}{{{E_1}}} = {\left( {\frac{{{T_2}}}{{{T_1}}}} \right)^4} = {\left( {\frac{{1200}}{{400}}} \right)^4} =3^4 = 81\)

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