Consider two walls, A and B, with the same surface areas and the same temperature drops across their thicknesses. The ratio of their thermal conductivities is kA/kB=4 and the ratio of the wall thickness is LA/LB=2. The ratio of heat transfer rates through the walls qA/qB is:(a) 0.5
(b) 1
(c) 2
(d) 4
(e) 8
(f) None of them
Answers
Answer:
(c) 2
Explanation:
Heat transfer across the walls due to conduction is given by:
where,
q = heat transfer rate
K = thermal conductivity
A = Area
ΔT = change in temperature
L = thickness
For wall A:
For wall B:
Because the change of temperature and area of walls are the same. Dividing both terms:
using values given in the question:
Therefore, the correct answer is:
(c) 2
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Answer:
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