# The end of two rods of different materials with their thermal conductivities, area of cross-section and lengths all in the ratio 1:2 are maintained at

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The end of two rods of different materials with their thermal conductivities, area of cross-section and lengths all in the ratio 1:2 are maintained at the same temperature difference. If the rate of flow of heat in the first rod is 4 cal//s. Then, in the second rod rate of heat flow in cal//s  will be
A. 1
B. 2
C. 8
D. 16

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because (dQ)/(dt) = (K(pir^(2))Delta theta)/ l
implies ((dQ)/(dt))_(2)/ ((dQ)/(dt))_(1) = (K_(2)xxr_(2)^(2) xx l_(1))/ (K_(1) xx r_(1)^(2) xx l_(2))= 1/2 xx 1/4 xx 2/1
implies ((dQ)/(dt))_(2) = ((dQ)/(dt))_(1)/4 = 4/4 = 1