Question

Heat is radiated between surface 1 and surface 2. The surface area of 1 is greater than that of 2. The fraction of radiation leaving surface 1 that is intercepted by surface 2 is __________ the fraction of radiation leaving surface 2 that is intercepted by surface 1.

A. greater than
B. less than
C. equal to
D. impossible to tell from the information provided

Answer 1

The fraction of radiation leaving the larger surface 1 that is intercepted by the smaller surface 2 is less than the fraction leaving the smaller surface 2 that is intercepted by the larger surface 1.

Step-by-step explanation:

The fraction of radiation leaving surface 1 that is intercepted by surface 2 is less than the fraction of radiation leaving surface 2 that is intercepted by surface 1. This is because radiation is emitted by surface 1 over a larger area, and only a portion of that radiation will intersect with the smaller area of surface 2. In contrast, the smaller surface 2 emits radiation over a smaller area, so a larger fraction of that radiation is likely to be intercepted by the larger surface 1.