A Sphere of Surface Area $1.25 \mathrm {~m} ^ { 2 }$

Multiple Choice

A sphere of surface area $1.25 \mathrm {~m} ^ { 2 }$ and emissivity 1.0 is at a temperature of $100 ^ { \circ } \mathrm { C }$ At what rate does it radiate heat into empty space? $\left( \sigma = 5.67 \times 10 ^ { - 8 } \mathrm {~W} / \mathrm { m } ^ { 2 } \cdot \mathrm { K } ^ { 4 } \right)$

A) 7.1 W
B) 0.71 mW
C) 3.7 W
D) 9.9 mW
E) 1.4 kW