Two identical rods of a metal are welded as shown in figure-4.39(a). 20 cal of heat flows through them in 4 minute. If the rods are welded as shown in figure-4.39(b), then the same amount of heat will flow in:

Options

A. 1 minute
B. 2 minute
C. 4 minute
D. 16 minute

Answer

A

Explanation

As we use `20=(kA(100-0)t_(1))/(2L)`
`implies 20=Q=(K(2A)(100-0)t_(2))/(L)`
`implies (t_(1))/(2)=2t_(2)`
`implies t_(2)=(t_(1))/(4)=(4)/(4)=1 min`