A Blackbody Sphere with a Radius of 10 Cm Is $T _ { \text {sphere } } \gg T _ { \text {enrition } }$

Multiple Choice

A blackbody sphere with a radius of 10 cm is at 400 K. The sphere is in a very low-temperature environment $T _ { \text {sphere } } \gg T _ { \text {enrition } }$ , so the rate at which thermal energy is radiated away from its surface is

A) 46 J/s.
B) 23 J/s.
C) 92 J/s.
D) 180 J/s.