Discussion Forum
Que.  The heat flow equation through a cylinder of inner radius r1 and outer radius r2 is desired to be written in the same form as that for heat flow through a plane wall. For wall thickness (r₂r₁) the area will be 
a.  A1 + A2/2 
b.  A1 + A2 
c.  A2 – A1/ log e (A2/A1) 
d.  A1 + A2/2 log e (A2/A1) 
Correct Answer:A1 + A2/2
