Refractive Index

Q. Two slits are made one millimetre apart and the screen is placed one metre away. What is the fringe separation when bluegreen light of wavelength $500\text{nm}$ is used?

1. $0.5\text{mm}$
2. $5\text{mm}$
3. $50\text{mm}$
4. $0.5\text{m}$

Q. If a light ray incident normally on one of the faces of a Prism of refractive index 2 and the emergent ray just graces the second face of the prism, then the angle of deviation is?

Q. Find the refractive index of glass with respect to water.
The refractive index of glass with respect to air is $\frac{3}{2}$ and the refractive index of water with respect to air is $\frac{4}{3}$ respectively.

1. $\frac{8}{9}$
2. $\frac{4}{9}$
3. $\frac{9}{4}$
4. $\frac{9}{8}$

Q.

What is optical path?

Q. A ray incident at an angle of incidence ${60}^{\circ }$ enters a glass sphere of refractive index $\mu =\sqrt{3}$. This ray is reflected and refracted at the farther surface of the sphere. The angle between reflected and refracted rays at this surface is

1. ${90}^{\circ }$
2. ${60}^{\circ }$
3. ${70}^{\circ }$
4. ${40}^{\circ }$

Q. 19.The order of magnitude of speed of light in cgs system is- 1. 8 2. 10 3. 6 4. 7

Q.

Explain refraction through a parallel-sided glass slab.

Q.

An unpolarized light beam is incident on the polarizer of a polarization experiment and the intensity of the light beam emerging from the analyzer is measured as $100Lumens$. Now, if the analyzer is rotated around the horizontal axis (direction of light) by $30°$ in clockwise direction, the intensity of emerging light will be________ Lumens.

Q. A ray of light travelling in transparent medium of refractive index $\mu$ falls on a surface separating the medium from air at an angle of incidence of ${45}^{\circ }$. For which of the following value of $\mu$ the ray can undergo TIR?

1. $\mu >1.33$
2. $\mu >1.4$
3. $\mu >1.2$
4. $\mu >1.25$

Q. What is the relation between refractive indices $\mu ,{\mu }_1$ and ${\mu }_2$ if the behaviour of light rays is as shown in figure.

1. $\mu >{\mu }_2>{\mu }_1$
2. $\mu <{\mu }_2<{\mu }_1$
3. $\mu <{\mu }_2;\mu ={\mu }_1$
4. ${\mu }_2<{\mu }_1;\mu ={\mu }_2$

Q. A bird in air looks at a fish below it inside in a transparent liquid in a tank. If the distance of the fish as estimated by the bird is $h_1$ and that of the bird as estimated by the fish is $h_2$, then the refractive index of the liquid is

1. $\frac{h_2}{h_1}$
2. $\frac{h_1}{h_2}$
3. $\frac{h_1+h_2}{h_1-h_2}$
4. $\frac{h_1-h_2}{h_1+h_2}$

Q. With a concave mirror, an object is placed at a distance $x_1$ from the principal focus away from the mirror, on the principal axis. The image is formed at a distance $x_2$ from the principal focus also away from the mirror. The focal length of the mirror is

1. $x_1{x}_2$
2. $\frac{(x_1+x_2)}{2}$
3. $\sqrt{\frac{x_1}{x_2}}$
4. $\sqrt{x_1{x}_2}$

Q.

What is the difference between absolute refractive index and relative refractive index

Q. In a Young's double slit experiment, a laser light of $560\text{nm}$ produces an interference pattern with consecutive bright fringes' separation of $7.2\text{mm}$. Now, another light is used to produce an interference pattern with consecutive bright fringes' separation of $8.1\text{mm}$. The wavelength of second light is $\text{nm}$.

Q. The index of refraction of diamond is $2.0$, velocity of light in diamond in $\text{cm/s}$ is approximately

1. $6\times {10}^{10}$
2. $3.0\times {10}^{10}$
3. $2\times {10}^{10}$
4. $1.5\times {10}^{10}$

Q.

(a) Figure 9.35 shows a cross-section of a ‘light pipe’ made of a glass fibre of refractive index 1.68. The outer covering of the pipe is made of a material of refractive index 1.44. What is the range of the angles of the incident rays with the axis of the pipe for which total reflections inside the pipe take place, as shown in the figure.

(b) What is the answer if there is no outer covering of the pipe?

Q. A ray of light is incident on the surface of a glass plate of refractive index $1.732$ at the polarizing angle. The angle of refraction is,

1. ${60}^{\circ }$
2. ${45}^{\circ }$
3. ${30}^{\circ }$
4. ${15}^{\circ }$

Q. A concave lens of glass refractive index 1.5 has both surfaces of same radius of curvature R. On immersion in a medium of refractive index 1.75, it will behave as a: (A) Convergent lens of focal length 3.5R (B) Convergent lens of focal length 3R (C) Divergent lens of focal length 3.5R (D) Divergent lens of focal length 3R

Q. A ray of light travels in the fashion as shown in the figure. After passing through water, the ray grazes along the water-air interface. The value of ${\mu }_g$ in terms of $i$ is

1. $\frac{1}{\sin i}$
2. $\frac{3}{\sin i}$
3. $\frac{2}{\sin i}$
4. $\frac{4}{\sin i}$

Q. Formation of a real image using a biconvex lens is shown below:


If the whole set up immersed in water without disturbing the object and the screen positions, what will one observe on the screen?

1. Magnified image
2. No change
3. Image disappears
4. Erect real image

Q. Consider a configuration of $n$ identical units, each consisting of three layers. The first layer is a column of air of height $h=\frac{1}{3}\text{cm}$, and the second and third layers are of equal thickness $d=\frac{\sqrt{3}-1}{2}\text{cm}$, and refractive indices ${\mu }_1=\sqrt{\frac{3}{2}}\text{and}{\mu }_2=\sqrt{3}$, , respectively. A light source $O$ is placed on the top of the first unit, as shown in the figure. A ray of light from $O$ is incident on the second layer of the first unit at an
angle of $\theta ={60}^{\circ }$
to the normal. For a specific value of $n$, the ray of light emerges from the bottom of the configuration at a distance $l=\frac{8}{\sqrt{3}}\text{cm}$, as shown in the figure. The value of $n$ is

Q. A light wave is incident normally on a glass slab of refractive index $\mathrm{1.5.}$ If $4\%$ of light gets reflected and the amplitude of the electric field of the incident light is $30{\text{Vm}}^{-1}$ then the amplitude of the electric field for the wave propagating in the glass medium will be :

1. $6{\text{Vm}}^{-1}$
2. $24{\text{Vm}}^{-1}$
3. $10{\text{Vm}}^{-1}$
4. $30{\text{Vm}}^{-1}$

Q.

A beam of light propagating in medium A with index of refraction n (A)passes across an interface into medium B with index of refraction n(B). The angle of incidence is greater than the angle of refraction; v(A) and v(B) denotes the speed of light in A and B. Then which of the following is true

1. v(A) > v(B) and n(A) > n(B)

2. v(A) > v(B) and n(A) < n(B)

3. v(A) < v(B) and n(A) > n(B)

4. v(A) < v(B) and n(A) < n(B)

Q. A ray of light passes from vacuum into a medium of refractive index $\mu$, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is

1. $2co{s}^{-1}\left(\frac{\mu }{2}\right)$
2. $co{s}^{-1}\left(\frac{\mu }{2}\right)$
3. $2si{n}^{-1}\left(\mu \right)$
4. $2si{n}^{-1}\left(\frac{\mu }{2}\right)$

Q.

What are the values of a. the angle of incidence and b. the angle of reflection for normal incidence on a plane mirror surface?

Q. Light is incident normally on the short face of a ${30}^{\circ }-{60}^{\circ }-{90}^{\circ }$ prism as shown in the figure. A liquid is poured on the hypotenuse of the prism. If the refractive index of the prism is $\sqrt{3}$, find the maximum value of refractive index of the liquid above which TIR dosen't take place.

1. $1.3$
2. $1.5$
3. $1.4$
4. $1.2$

Q. A double convex lens, lens made of a material of refractive index ${\mu }_1$ is placed inside two liquids or refractive indices ${\mu }_2$ and ${\mu }_3$, as shown ${\mu }_2>{\mu }_1>{\mu }_3$. A wide, parallel beam of light is incident on the lens from the left.

1. A single convergent beam
2. Two different convergent beams
3. Two different divergent beams
4. A convergent and a divergent beam

Q.

What do you mean by optically denser and optically rarer mediums?

Q. minimum magnifying power of a simple microscope is 8. maximum magnifying power of the microscope will b

Q. A small pin fixed on a table top is viewed from above from a distanceof 50cm. By what distance would the pin appear to be raised if it isviewed from the same point through a 15cm thick glass slab heldparallel to the table? Refractive index of glass = 1.5. Does the answerdepend on the location of the slab?