Question

The temperature at which a black body of unit area loses its energy at the rate of $1$ joule/second is

• A. $-{65}^{o}C$
• B. ${65}^{o}C$
• C. $65K$
• D. None of these

Answer 1

The correct option is C $65K$

Area is unity so $E=\sigma T^4$ which is $1J/s$ so we have $T^4=1/\sigma =1/(5.67\times {10}^{-8})=1763.66\times {10}^4$

so $T=64.8K$

Option c is correct.