Two identical square rods of metal are welded end to end as shown in the figure ( 1 ) , 20 cal of heat flows through it in 4 min . If the rods are welded as shown in the figure ( 2 ) , the same amount of heat will flow through the rods in

Question

Two identical square rods of metal are welded end to end as shown in the figure ( 1 ) , 20 cal of heat flows through it in 4 min . If the rods are welded as shown in the figure ( 2 ) , the same amount of heat will flow through the rods in, 1 min, 2 min, 4 min, 16 min

MARKS App · Accepted Answer

Figure (1) → series combination Figure (2) → parallel combination Thermal resistance for each block to be R Then Thermal resistance for the case I R 1 = 2 R Thermal resistance for the case II R 2 = R /2 Thermal resistance for case II I 1 = Δ T R 1 I 2 = Δ T R 2 ⇒ 4 I 1 = I 2 4 Δ Q 1 Δ t 1 = Δ Q 2 Δ t 2 if Δ Q 1 = Q 2 then 4 Δ t 2 = Δ t 1 Δ t 2 = Δ t 1 / 4 = 4 4 = 1 min

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