Q. Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 30 minutes. The ratio of their thermal conductivities will be
A) 1.5
B) 1
C) $2/3$
D) 4
Explanation
(a) $Q = \frac{KA(\theta_{1} - \theta_{2})t}{l}$; in both the cases, $A,l$ and $(\theta_{1} - \theta_{2})$ are same so $Kt =$ constant
$\Rightarrow \frac{K_{1}}{K_{2}} = \frac{t_{2}}{t_{1}} = \frac{30}{20} = \frac{3}{2} = 1.5$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.