Which of the following circular rods (given radius `r` and length `l`) each made of the same material and whose ends are maintained at the same temperature will conduct most heat?

Options

A. `r=2r_(0),l=2l_(0)`
B. `r=2r_(0),l=l_(0)`
C. `r=r_(0) , l=2l_(0)`
D. `r=r_(0), l=l_(0)`

Answer

B

Explanation

Use `R_("Heat")=(l)/(KA)=(l)/(K pir^(2))`