Question

o keep yourself warm in the winter, you heat a solid metal ball and place it on a stand in the center of your room. The ball has a radius of 20.0 cm and an emissivity of 0.790. If your room has a temperature of 15°C, what is the net power radiated by the ball initially, when the ball's temperature is 200°C?

Answer 1

Answer:

1.7135 x 10^10 J / s

Explanation:

R = 20 cm = 0.2 m

e = 0.79

To = 15 degree C = 15 + 273 = 288 K

T = 200 degree C = 200 + 273 = 473 K

Energy radiated per unit time = A x e x (T^4 - To^4)

Power radiated = 4 x 3.14 x 0.2 x 0.2 x 0.79 x (473^4 - 288^4)

                          = 1.7135 x 10^10 J / s