NEET Practice Questions - Physics - Wave Optics

Young's double slit experiment is first performed in air and then in a medium other than air. It is found that 8th bright fringe in the medium lies where 5th dark fringe lies in air. The refractive index of the medium is nearly 

(a)1.25 

(b) 1.59 

(c) 1.69

(d) 1.78 

Two polarids $P_1 and P_2$ are placed with their axis perpendicular to each other. Unpolarised light $I_o$ is incident on $P_1$. A third polaroid $P_3$ is kept in between $P_1 and P_2$ such that its axis makes an angle ${45}^{°}$ with that of $P_1$. The intensity of transmitted light through $P_2$

(a)$\frac{I_o}{2}$

(b) $\frac{I_o}{4}$

(c) $\frac{I_o}{8}$

(d) $\frac{I_o}{16}$

The interference pattern is obtained with two coherent light sources of intensity ratio n. In the interference pattern, the ratio $\frac{I_{max}-I_{min}}{I_{max}+I_{min}}$ will be

(a) $\frac{\sqrt{n}}{n+1}$             (b) $\frac{2\sqrt{n}}{n+1}$

(c) $\frac{\sqrt{n}}{{\left(n+1\right)}^2}$         (d) $\frac{2\sqrt{n}}{{\left(n+1\right)}^2}$