Q. If $l$ is length $A$ is the area of cross section and $K$ is thermal conductivity, then the thermal resistance of the block is given by
A) $K\ l\ A$
B) $1$/ $K\ l\ A$
C) $l + KA\ $
D) $l$ / $KA$
Explanation
(d) $R_{th} = \ \frac{\mathrm{\Delta}T}{(\mathrm{\Delta}Q/\mathrm{\Delta}t)} = \frac{\mathrm{\Delta}x}{KA} = \frac{l}{KA}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.