One end of a capillary tube is dipped in water, the rise of water column is ' $h$ '. The upward force of 98 dyne due to surface tension is balanced by the force due to the weight of the water column. The inner circumference of the capillary is $\left(\right.$ surface tension of water $\left.=7 \times 10^{-2} \mathrm{Nm}^{-1}\right)$

Light of wavelength $\lambda$ strikes a photoelectric surface and electrons are ejected with energy E . If $E$ is to be increased to twice the original value, the wavelength changes to $\lambda_1$

For ideal non-rigid diatomic gas, the value of $\frac{\mathrm{R}}{\mathrm{C}_{\mathrm{V}}}$ is nearly $\left(\gamma=\frac{\mathrm{C}_{\mathrm{P}}}{\mathrm{C}_{\mathrm{V}}}=\frac{9}{7}\right)$

Two long straight wires A and B carrying equal current 'I' were kept parallel to each other at distance ' $d$ ' apart. Magnitude of magnetic force experienced by length $L$ of wire $A$ is ' $F$ '. If the distance between the wires is made half and currents are doubled, force $F_2$ on length $L$ of wire $A$ will be