A spherical metal ball of radius 1 cm is suspended in a room at 300 K temperature. Inside the sphere there is a battery operated heater which maintains the temperature of the ball at 1000 K. Find the

Question

A spherical metal ball of radius 1 cm is suspended in a room at 300 K temperature. Inside the sphere there is a battery operated heater which maintains the temperature of the ball at 1000 K. Find the power of the heater if emissivity of the metal ball is 0.3.

TestHub · Accepted Answer

P = e σ A ( T 4 − T 0 4 ​ ) = 0.3 × 5.67 × 1 0 − 8 × 4 π 0.01 2 ( 100 0 4 − 30 0 4 ) = 21.2 W. The printed 22 W is a little higher (about 4%), likely rounding.

Physics - Heat & Thermo Question with Solution | TestHub

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