JEE Advanced2014PhysicsThermal Properties of MatterActual
Parallel rays of light of intensity I = 912 W m - 2 are incident on a spherical black body kept in surroundings of temperature 300 K. Take Stefan-Boltzmann constant σ = 5.7 × 10 -8 W m - 2 K - 4 and assume that the energy exchange with the surroundings is only through radiation. The final steady state temperature of the black body is close to
Options
- A330 K
- B660 K
- C990 K
- D1550 K
Correct answer
A. 330 K
Step-by-step solution
Rate of radiation energy lost by the sphere = Rate of radiation energy incident on it ⇒ σ × 4 π r 2 T 4 - 300 4 = 912 × π r 2 ⇒ T = 11 × 10 2 ≈ 330 K