Two metal rods are to be used to conduct heat from a region at 100°C to a region at 0°C as shown in the figure. The rods can be placed in parallel, as shown on the left, or in series, as on the right. When steady state flow is established, the heat conducted in the series arrangement is
A) greater than the heat conducted with the rods in parallel.
B) the same as the heat conducted with the rods in parallel.
C) less than the heat conducted with the rods in parallel.

Question

Two metal rods are to be used to conduct heat from a region at 100°C to a region at 0°C as shown in the figure. The rods can be placed in parallel, as shown on the left, or in series, as on the right. When steady state flow is established, the heat conducted in the series arrangement is 
A) greater than the heat conducted with the rods in parallel. 
B) the same as the heat conducted with the rods in parallel. 
C) less than the heat conducted with the rods in parallel.

Quizplus · Accepted Answer

In the series arrangement, the heat must flow through both rods in order to reach the colder region, whereas in the parallel arrangement, the heat can flow through either of the rods. This means that in the series arrangement, the colder rod will be a bottleneck to the flow of heat, slowing down the rate of heat conduction. Therefore, the heat conducted in the series arrangement will be less than the heat conducted in the parallel arrangement.

Two Metal Rods Are to Be Used to Conduct Heat