A wall is built from two different insulating materials joined face-to-face
PHYSICS · Single correct · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A wall is built from two different insulating materials joined face-to-face. Material X has a much larger thermal conductivity than Material Y, but both layers have the same thickness and area. Which statement best describes the overall thermal resistance of the wall?
(a) It is dominated by Material X because its greater conductivity lowers the total resistance.
(b) Both materials contribute equally because their thicknesses are identical.
(c) It is dominated by Material Y because its larger resistance adds most to the total.
(d) Neither material dominates; the thermal resistance depends only on the temperature difference across the wall.