Refraction at Planar Surface

Q.

State the Snell’s laws of refraction of light.

Q.

Draw the diagrams to show the refraction of light from (i) air to glass, and (ii) glass to air. In each diagram, label the incident ray, refracted ray, the angle of incidence (i) and the angle of refraction (r).

Q.

Why do swimming pool appears shallow than its actually is? What phenomenon is responsible for it?

1. Reflection of light

2. Diffusion of light

3. Refraction of light

4. Eye defect

Q.

What are the factors affecting refraction?

Q. A ray of light enters a rectangular glass slab of refractive index $\sqrt{3}$ at an angle of incidence ${60}^{\circ }.$ It travels a distance of 5 cm inside the slab and emerges out of slab. The perpendicular distance between the incident ray and the emergent ray is

1. $5/\sqrt{3}cm$
2. $\sqrt{3}/5cm$
3. $5/3cm$
4. $5/2cm$

Q.

A ray of green light enters a liquid from air, as shown in Fig. 4.21. The angle 1 is ${45}^{\circ }$ and angle 2 is ${30}^{\circ }$.

(a) Find the refractive index of the liquid.

(b) Show in the diagram the path of the ray after it strikes the mirror and re-enters in the air. Mark in the diagram the angles wherever necessary.

(c) Redraw the diagram if the plane mirror becomes normal to the refracted ray inside the liquid. State the principle used.

Q. In a vessel of depth $21\text{cm}$, upto what height the water should be filled so that now it appears to be half filled if viewed from the top? $(\text{Take}{\text{n}}_{\text{w}}=\frac{4}{3})$

1. $22\text{cm}$
2. $21\text{cm}$
3. $11\text{cm}$
4. $12\text{cm}$

Q.

A ray of light is incident on a plane mirror at an angle of incidence of ${30}^{\circ }$. The deviation produced by the mirror is

1. ${30}^{\circ }$

2. ${60}^{\circ }$

3. ${90}^{\circ }$

4. ${120}^{\circ }$

Q.

A vessel of depth $2h$ is half-filled with a liquid of refractive index $\sqrt{2}$ in the upper half and with a liquid of refractive index $2\sqrt{2}$ in the lower half. The liquids are immiscible. The apparent depth of the inner surface of the bottom of the vessel will be;

1. $\frac{3h}{4}\sqrt{2}$

2. $\frac{h}{\sqrt{2}}$

3. $\frac{h}{3\sqrt{2}}$

4. $\frac{h}{2\left(\sqrt{2}+1\right)}$

Q.

The critical angle for light entering from medium X into medium Y is q. The speed of light in medium X is u. The speed of light in medium Y is

1. $\frac{u}{\cos q}$

2. u (1 – $\cos q$)

3. u($\cos q$)

4. $\frac{u}{\sin q}$

Q. How to calculate angle of refraction when angle of incidence and angle of emergence is given?

Q.

The diagram alongside shows the refraction of a ray of light from air to a liquid.

(a) Write the values of (i) angle ofincidence, and (ii) angle of refraction.

(b) Use Snell's law to find the refractive index of liquid with respect to air.

Q.

Refractive index of eye lens is

1. $0.80$

2. $1.00$

3. $1.33$

4. $1.44$

Q.

Fig. 4.62 shows a point source P inside a water container. Three rays A, B and C starting from the source P are shown up to the water surface.
(a) Show in the diagram the path of these rays after striking the water surface. The critical angle for water-air surface is ${48}^{\circ }$.
(b) Name the phenomenon which the rays A, B and C exhibit.

Q.

In Fig. 4.18, a ray of light A incident from air suffers partial reflection and refraction at the boundary of water.

(a) Complete the diagram showing (i) the reflected ray B and (ii) the refracted ray C.

(b) How are the angles of incidence i and refraction r related?

Q. An air bubble inside water behaves like a diverging lens. Explain.

Q. A vessel of depth x is half filled with oil of refractive index ${\mu }_2.$ and half with water of refractive index ${\mu }_1.$ The apparent depth of the vessel when viewed from above is :

1. $\frac{x({\mu }_1+{\mu }_2)}{2{\mu }_1{\mu }_2}$
2. $\frac{x{\mu }_1{\mu }_2}{2({\mu }_1+{\mu }_2)}$
3. $\frac{x{\mu }_1{\mu }_2}{({\mu }_1+{\mu }_2)}$
4. $\frac{2x({\mu }_1+{\mu }_2)}{{\mu }_1{\mu }_2}$

Q.

When a ray of light from air enters a denser medium, it :

(a) bends away from the normal

(b) bends towards the normal

(c) goes undeviated

(d) is reflected back.

Q.

Find the critical angle for a ray of light travelling from glass to air?

[ ${\mu }_g$ = $\sqrt{2}$ , ${\mu }_a$ = 1 ]

1. 90°

2. 45°

3. 30°

4. cannot be determined

Q.

An endoscope is employed by a physician to view the internal parts of a body organ. It is based on the principle of:

1. Refraction

2. Total internal reflection

3. Reflection

4. Dispersion

Q.

A rectangular tank of depth $8$ meter is full of water $n=4/3$, the bottom is seen at the depth:

1. $6cm$

2. $8/3cm$

3. $8cm$

4. $10cm$

Q.

A light ray suffers reflection and refraction at the boundary in passing from air to water. Draw a neat labelled ray diagram to show it.

Q. Refractive index of glass with respect to water is 1.125. If the absolute refractive index of glass is 1.5, then the absolute refractive index of water is ___.

1. 1.5
2. 1.33
3. 1.7
4. 1.9

Q.

A vertical ray of light strikes the horizontal surface of some water : (a) What is the angle of incidence ? (b) What is the angle of refraction ?

Q.

Snell's law of refraction of light states that

1. 

2. 

3. 

4. 

Q.

(a) How can you bend light away from the normal ? (b) How must light travel out of a substance if it is not going to be refracted ?

Q.

What is the value of x in the figure shown?

1. ${30}^{\circ }$

2. ${90}^{\circ }$

3. ${60}^{\circ }$

4. ${45}^{\circ }$

Q.

Draw a ray diagram showing the path of rays of light when it enters with oblique incidence from air into water.

Q.

Does the Doppler effect apply to light?

Q. The length of a vertical stick at the surface of the lake appears 12cm to a fish under water. If refractive index of water is 4/3 then actual length of stick above water is

1. $16cm$
2. $9cm$
3. $12cm$
4. $3cm$