Question

Let the coefficients of thermal conductivity of three metals $P,Q$ and $R$ are in the ratio $1:2:3$. For the same quantity of heat is to flow per second per unit area of each, the corresponding temperature gradients should be in the ratio.

• A. $1:2:3$
• B. $3:2:1$
• C. $6:3:2$
• D. $4:3:2$

Answer 1

The correct option is C $6:3:2$

We know that heat is given as $Q=KA\Delta {\theta }_{x}t$

Where $\Delta {\theta }_x$ is temperature gradient.

Given that $t=1sec$ and $A$ as unit area.

So $Q=K\Delta {\theta }_x$ so to keep the product of $K$ and temperature gradient constant we need the temperature gradient in

following ratio $1:\frac{1}{2}:\frac{1}{3}=6:3:2$

Option C is correct.