In Young's double slit interference experiment, using two coherent sources of different amplitudes, the intensity ratio between bright to dark fringes is $5: 1$. The value of the ratio of resultant amplitudes of bright fringe to dark fringe is

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 $\left(\gamma=\frac{\mathrm{C}_{\mathrm{P}}}{\mathrm{C}_{\mathrm{V}}}=\frac{9}{7}\right)$