A wire of length $$L$$ and radius $$r$$ is clamped at one end. If its other end is pulled by a force $$F$$, its length increases by $$l$$. If the radius of the wire and the applied force both are reduced to half of their original values keeping original length constant, the increase in length will become:

The temperature of a gas having $$2.0 \times 10^{25}$$ molecules per cubic meter at $$1.38 \mathrm{~atm}$$ (Given, $$\mathrm{k}=1.38 \times 10^{-23} \mathrm{JK}^{-1}$$) is :

If the distance between object and its two times magnified virtual image produced by a curved mirror is $$15 \mathrm{~cm}$$, the focal length of the mirror must be:

A plane electromagnetic wave of frequency $$35 \mathrm{~MHz}$$ travels in free space along the $$X$$-direction. At a particular point (in space and time) $$\vec{E}=9.6 \hat{j} \mathrm{~V} / \mathrm{m}$$. The value of magnetic field at this point is :