Atmospheric Refraction

Q.

What are the conditions for total internal reflection?

Q.

What is the reason for the diamond sparkle?

Q. Explain the mirage effect.

Q.

The refractive index of glass with respect to air is 1.5. What is the value of the refractive index of air with respect to glass?

1. 1.5

2. 2.5

3. 1.33

4. 0.75

5. 0.67

Q.

What is the phenomenon responsible for the blue colour of the sky?

Q. Why do stars seem higher than they actually are ? Illustrate your answer with the help of a diagram.

Q. A light ray is incident perpendicularly to one face of a ${90}^0$prism and is totally internally reflected at the glass-air interface.
If the angle of reflection is ${45}^0$, we conclude that the refractive index 'n' will be

Diagram

1. $n>\frac{1}{\sqrt{2}}$
2. $n>\sqrt{2}$
3. $n<\frac{1}{\sqrt{2}}$
4. $n<\sqrt{2}$

Q.

Do the colours of white light travel at same speed through the air?

Q.

What will be the colour of sky if there is no atmosphere on the earth?

1. Dark blue

2. Red

3. Black

4. White

Q.

Which phenomenon is responsible for early sunrise and late sunset?

1. Refraction of light

2. Reflection of light

3. Total internal reflection

4. Dispersion of light

Q. The twinkling of stars is due to atmospheric :
(a) reflection of light (b) dispersion of light
(c) interference of light (d) refraction of light

Q. Refractive index of water with respect to air is 4/3 and glass is 3/2.Find refractive index of glass with respect to water.

Q. Explain why, if we look at objects through the hot air over a fire, the objects appear to be moving (or shaking) slightly.

Q.

Is the position of a star as seen by us its true position? Justify your answer.

Q. We can see the sun before it has actually risen above the horizon (advance sunrise) and can see the sun for sometime after it has set below the horizon (delayed sunset), all because of atmospheric refraction.

1. True
2. False

Q. Total internal reflection can happen only when light ray passes from denser to rarer medium.

1. True
2. False

Q. Match the following :

LIST I	LIST II
A) Rainbow	1) Scattering of light
B) Twinkling of stars	2) Dispersion of light
C) Blue colour of sky	3) Fluctuation of the refraction index in atmosphere layers
D) Advancement of sunrise and delay of sunset	4) Refraction of light

1. A-4, B-1, C-3, D-2
2. A-1, B-2, C-4, D-3
3. A-2, B-3, C-1, D-4
4. A-3, B-4, C-2, D-1

Q. Name the phenomenon that causes twinkling of the star on a clear sky.

1. Atmospheric refraction
2. Dispersion of light
3. Reflection of light
4. Interference of light

Q. The shape of a rainbow when viewed from an aircraft flying very high is .

1. Arc
2. Circle
3. Hemisphere

Q.

What is the reason for the twinkling of stars?

1. dispersion

2. scattering

3. refraction

4. reflection

Q.

why is the colour of clear sky blue?

Q.

(a) What is atmospheric refraction ? What causes atmospheric refraction ?
(b) Why do stars twinkle on a clear night ?
(c) Explain why, the planets do not twinkle at night.

Q. Why do Stars twinkle? Give the reason.

Q. Name two effects produced by the atmospheric refraction.

Q.

Match the statements of Column A with those of Column B.

Column A	Column B
(A) Blue color of sky (B) Mirage (C) Twinkling of stars (D) Formation of rainbow	(a) Total internal reflection (b) Scattering of light (c) Dispersion (d) Refraction

1. A→b; B → a; C→d; D→C;

2. A→a; B→b; C→C; D→d

3. A→b; B→ c; C → b; D→a;

4. A→C; B→d; C→b; D→ ́a;

Q.

The observed blue color of the sky is due to the phenomenon of scattering of light.

1. True
2. False

Q.

A step index fibre has a relative refractive index of $0.88\%$. What is the critical angle at the core cladding interface?

1. ${60}^0$

2. ${75}^0$

3. ${45}^0$

4. None of these

Q. Name the phenomenon due to which the stars seem higher in the sky than they actually are.

Q. For an angle of incidence of ${45}^0$ at the top surface of a glass slab as shown in the figure, What is the maximum refractive index of glass for total internal reflection to take place? [For water $\mu =\frac{4}{3}$]

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

Q.

Light takes $T_1$ sec to travel a distance $x$ In a vacuum and the same light takes $T_2$ sec to travel $10cm$ in a medium. The critical angle for the corresponding medium will be: