Question

Two rods $A$ and $B$ of same metal and of same cross-section have length in the ratio $1:2$. One end of each rod is at $0^o$C and temperature of other ends are 30${}^o$C and 40${}^o$C respectively. Which of the rod will have higher flow of heat?

• A. Rod A
• B. Rod B
• C. Both will have same
• D. Depends upon the shape

Answer 1

The correct option is A Rod A

Heat conduction through a rod is given as: $H=kA\frac{\Delta T}{L}$
As the cross-sectional area remains constant, the heat flow varies as $\frac{\Delta T}{L}$
Length of A : Length of B :: 1:2
Temp diff of A : Temp diff of B :: 3:4
Heat of A : Heat of B :: 3:2
Hence, Rod A will have higher flow of heat.