Question:-
Consider two infinitely long blackbody concentric cylinders with a diameter ratio D2/D1 = 3. The shape factor for the outer cylinder with itself will be

Option (A)
0
Option (B)
1/3
Option(C)
2/3
Option(D)
1
Correct Option:
(C)
Question Solution:
Surface enclosure F21+ F22 = 1
F22 = 1-F21
A1F12 = A2F21
pD1hF12 = pD2.F21h
F21 = (D12). F12 = F21 = (1/3) x 1 = 1/3
(F22 = 1-1/3= 2/3)
question-answer-faq-3076