Two metal rods 1 and 2 of same lengths have same temperature difference between their ends. Their thermal conductivities are K1 and K2 and cross sectional areas A1 and A2, respectively. If the rate of heat conduction in 1 is four times that in 2, then
The relation is as follows:
QT=KAΔTd
∵(QT)1=4(QT)2
K1A1ΔTd=4K2A2ΔTd
K1A1=4K2A2
Hence (b) is the correct option.