A ray of light incident on one face of an equilateral glass prism having refractive index $\sqrt{2}$, produces the emergent ray which just grazes along the adjacent face. The value of angle of incidence is $(\sin 90^\circ = 1)$
$\left(\sin 30^\circ = \dfrac{1}{2}\right)\left(\sin 45^\circ = \dfrac{1}{\sqrt{2}}\right)$

An unpolarised light of intensity $64 \text{ Wm}^{-2}$ passes through three polarizers successively such that the transmission axis of last polarizer is crossed with the first. The intensity of the emerging light is $6 \text{ Wm}^{-2}$. The angle between the transmission axis of the first two polarizers is

In Young's experiment, the intensity ratio of the maxima and minima in an interference pattern produced by two coherent sources is $36 : 1$. The ratio of the amplitudes of the two individual sources will be

For obtaining maximum contrast between the bright and dark fringes in an interference pattern, the intensities of the two light coherent sources should be