The lengths and radii of two rods made of same materials are in the ratio of 1:2 and 2:3 respectively, if the temperature difference between the ends for the two rods be the same, then in steady state, the amount of heat flowing through them will be in the ratio

given l1l2=12K=constant= coefficient of thermal conductivityr1r2=23 ( here r is radius of the cross section)Δθ=constant= temperature differenceQ1Q2=?Power P=Qt=KA(θ1-θ2)l=KA∆θl=Kπr2∆θlQtαr2lPαr2lP1P2=r1r22×l2l1P1P2=232×21P1P2=49×21=89 P1P2=89 is ratio of amount of heat flow per second