(a) Define thermal conductivity and clearly state its SI unit. (b) Starting from the…
PHYSICS · Subjective · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter
Problem
(a) Define thermal conductivity and clearly state its SI unit.
(b) Starting from the definition of thermal conductivity, obtain an expression for the steady–state rate of heat flow through a uniform slab in terms of its cross-sectional area, thickness, and the temperature difference between its two faces.
(c) A certain insulating board is required to limit the heat loss through a wall of area 6.0 m² to not more than 120 W when the temperature difference across it is 30 K. Explain, without doing any numerical calculation, whether the required thickness of the board will be larger or smaller if a material of lower thermal conductivity is chosen in place of the original one. Justify your answer qualitatively.