Refractive Index

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. Light is incident from air on oil at an angle of ${30}^{\circ }.$ After moving through oil-1 and another medium oil-2, it enters glass and then it enters water. If the refractive indices of glass and water are 1.5 and 1.3, respectively, find the angle which the ray makes with normal in water.

1. $si{n}^{-1}\left(\frac{1}{2.4}\right)$
2. $si{n}^{-1}\left(\frac{1}{2.8}\right)$
3. $si{n}^{-1}\left(\frac{1}{2.5}\right)$
4. $si{n}^{-1}\left(\frac{1}{2.6}\right)$

Q. A ray of light is incident on a transparent glass slab of refractive index 1.62. If the reflected and refracted rays are mutually perpendicular, what is the angle of incidence?

1. $ta{n}^{-1}\left(1.62\right)$
2. $co{t}^{-1}\left(1.62\right)$
3. $si{n}^{-1}\left(1.62\right)$
4. $co{s}^{-1}\left(1.62\right)$

Q.

Refractive index for a material for infrared light is

[CPMT 1984]

1. Equal to that for red colour of light

2. Equal to that of ultraviolet light

3. Less than for ultraviolet light

4. Greater than that for ultraviolet light

Q.

The refractive index of a certain glass is 1.5 for light whose wavelength in vacuum is 6000 Å. The wavelength of this light when it passes through glass is

[NCERT 1979; CBSE PMT 1993; MP PET 1985, 89]

1. 4000 Å

2. 15000 Å

3. 9000 Å

4. 6000 Å

Q.

The ratio of the refractive index of red light to blue light in air is
[CPMT 1978]

1. Equal to unity

2. Greater than unity

3. Less than unity

4. Less as well as greater than unity depending upon the experimental arrangement

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.

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.

The refractive index of a piece of transparent quartz is the greatest for
[MP PET 1985, 94]

1. Green light

2. Yellow light

3. Violet light

4. Red light

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