The rate of heat conduction through a cylindrical rod is $Q_1$. The temperatures at the ends of the rod are $T_1$ and $T_2$. If all the dimensions of the rod are doubled while keeping the temperatures the same,the new rate of heat conduction is $Q_2$. Then:

On a cold morning,a metal surface will feel colder to touch than a wooden surface because

If the radius and length of a copper rod are both doubled,the rate of flow of heat along the rod increases ....... times.

The lengths of two rods made of the same metal and having the same area of cross-section are $0.6 \ m$ and $0.8 \ m$ respectively. The temperatures at the ends of the first rod are $90^{\circ}C$ and $60^{\circ}C$,and those for the second rod are $150^{\circ}C$ and $110^{\circ}C$. For which rod will the rate of heat conduction be greater?

The two opposite faces of a cubical piece of iron (thermal conductivity $= 0.2 \text{ CGS units}$) are at $100^{\circ}C$ and $0^{\circ}C$ in ice. If the area of a surface is $4 \text{ cm}^2$,then the mass of ice melted in $10 \text{ minutes}$ will be ...... $\text{gm}$.

If the thermal conductivity of aluminum is $0.5 \ cal/cm \cdot s \cdot ^\circ C$,then the temperature gradient required to conduct $10 \ cal/s \cdot cm^2$ in the steady state is ...... $^\circ C/cm$.