NEET2015PhysicsThermal Properties of MatterActual
A copper ball 2 ~cm in radius is heated in a furnace to 327^ C . If its emissivity is 0.3 , at what rate does it radiate energy?
Options
- A1.72 ~W
- B2.73 ~W
- C11.0 ~W
- D2.15 ~W
Correct answer
C. 11.0 ~W
Step-by-step solution
The surface area of the ball A=4 r^2=(4 )(0.02 ~m )^2=0.005 ~m ^2 and its absolute temperature is aligned T & =327+273=600 ~K . Hence P & =e A T^4 & = (0.3 5.67 10⁻⁸ 0.005 (600)^4 . & =11.0 ~W aligned