### NEET Solved Paper 2017 Question 41

##### Question: A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be

#### Options:

A) 1800

B) 225

C) 450

D) 1000

## Show Answer

#### Answer:

Correct Answer: A

#### Solution:

- Rate of power loss $ r\propto R^{2}T^{4} $ $ \frac{r _1}{r _2}=\frac{R_1^{2}T_1^{4}}{R_2^{2}T_2^{4}} $ $ =4\times \frac{1}{16} $ $ \frac{450}{r _2}=\frac{1}{4} $ $ r _2=1800,watt $