Q. 13.8( 4 Votes )

A uniform slab of dimension 10 cm × 10 cm × 1 cm is kept between two heat reservoirs at temperatures 10°C and 90°C. The larger surface areas touch the reservoirs. The thermal conductivity of the material is 0.80 W m–1 °C–1. Find the amount of heat flowing through the slab per minute.

Answer :

Area of the uniform slab: A = 10× 10 cm2 = 100 cm2 = 0.01 m2
Height of the slab : x = 1 cm = 0.01 m
Temperature difference of two heat reservoirs:
ΔT = 90-10=80° C
The thermal conductivity of the material: K=0.80 W m–1 °C–1.
Formula used:
Rate of amount of heat flowing is given as:

Here, Δθ is the amount of heat transferred , ΔT is the temperature difference, K is the thermal conductivity of the material, A is the area of cross section of the material and x is the thickness of the material.
Substituting we get,

Hence, the amount of heat flowing through slab is 3840 J/min.

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