You are testing thermal conduction through two different materials,A and B,of the same cross-sectional area.Material A is twice as thick as material B,and the thermal conductivity of material A is three times higher than that of material B.What is the thermal resistance of A divided by the thermal resistance of B?
A)6.0
B)1.5
C)5.0
D)0.67
E)0.17

Question

Quizplus · Accepted Answer

The thermal resistance (R) of a material is defined as R=(thickness of material)/(thermal conductivity of material x cross-sectional area of material).

Let's assume the thickness of material B is "t". Therefore, the thickness of material A is "2t" (as given in the question).

Now, the thermal resistance of material B will be Rb = t/(kb*A), where kb is the thermal conductivity of material B.

The thermal resistance of material A will be Ra = 2t/(3kb*A), where 3kb is the thermal conductivity of material A (given in the question).

So, Ra/Rb = [2t/(3kb*A)]/[t/(kb*A)] = 2/3, which is equivalent to 1.5.

Therefore, the thermal resistance of A divided by the thermal resistance of B is 1.5.

You Are Testing Thermal Conduction Through Two Different Materials,A and B,of