Critical Angle

Q.

A ray of light from a denser medium strikes a rarer medium at an angle of incidence i as shown in the figure. The reflected and refracted rays make an angle of ${90}^{\circ }$ with each other. The angles of reflection and refraction are r and r'. The critical angle is

1. $si{n}^{-1}\left(tanr\right)$

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

3. $si{n}^{-1}\left(tan{r}^{\prime }\right)$

4. $ta{n}^{-1}\left(tani\right)$

Q. Can I get all numericals from the light chapter

Q.

What is meant by the statement 'the critical angle for diamond is $24{}^{\circ }$?

Q. A light ray is travelling from denser to rarer medium. The angle of incidence is equal to the critical angle. Then which of the following statements is/are true?

1. The angle of refraction is 90 degrees.
2. The refracted ray passes along the boundary separating the two medium.
3. The incident ray bounces back to the denser medium.
4. The incident ray passes undeviated from denser medium to rarer medium.

Q.

The refractive index of air with respect to glass is expressed as ${}_g{\mu }_a$ = $\frac{sini}{sinr}$.

(a) Write down a similar expression for ${}_g{\mu }_a$ in terms of the angles i and r.

(b) If angle r = ${90}^{\circ }$, what is the corresponding angle i called?

(c) What is the physical significance of the angle i in part (b)?

Q.

Define :angle of emergence

Q.

A light ray incident normally on a plane mirror suffers a deviation of

1. 0°

2. 90°

3. 180°

4. 360°

Q.

Calculate the critical angle of an optical fibre without cladding if the glass has a refractive index of 1.56.

1. 40^o

2. 39.9^o

3. 30^o

4. 90^o

Q.

What are the factors that affect the critical angle of the medium?

Q. What is critical angle? Explain it with a neat ray diagram.

Q.

Explain the shining of an air bubble in water.

Q.

Critical angle is that angle of incidence in the denser medium for which the angle of refraction in rarer medium is

1. ${60}^{\circ }$

2. $0^{\circ }$

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

4. ${180}^{\circ }$

Q.

How fringes are formed?

Q.

Critical angle of glass is ${\theta }_1$ and that of water is ${\theta }_2$. The critical angle for water and glass surface would be:
$({\mu }_g=\frac{3}{2},{\mu }_w=\frac{4}{3})$

1. Less than ${\theta }_2$

2. Between ${\theta }_{1}and{\theta }_2$

3. Greater than ${\theta }_2$

4. Less than ${\theta }_1$

Q.

The critical angle will be maximum when light travels from

1. glass to air

2. water to air

3. glass to water

4. water to glass

Q.

What are some real life examples of total internal refracion

Q.

The refractive index of the material of the prism and liquid are $1.56$ and $1.32$ respectively. What will be the value of θ?

1. $sin\theta \ge \frac{13}{11}$

2. $sin\theta \ge \frac{\sqrt{3}}{2}$

3. $sin\theta \ge \frac{1}{\sqrt{2}}$

4. $sin\theta \ge \frac{11}{13}$

Q.

Boojho made light from a laser torch to fall on a prism. Will he be able to observe a band of seven colours? Explain with a reason.

Q.

A ray of monochromatic light enters a liquid from air as shown in the diagram given below.

The two angles on the surface of separation of liquid and air, when the ray of light moves out from the liquid to air is :

1. 45^o and 30^o

2. 30^o and 45^o

3. 75^o and 15^o

4. 15^o and 75^o

Q. How angle of bending of light depend on wavelength of the light ?

Q.

If a ray of light strikes the surface of separation at ______________ degrees, the ray goes undeviated.

Q.

Critical angle is that angle of incidence in the denser medium for which the angle of refraction in rarer medium is

1. $0^{\circ }$

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

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

4. ${180}^{\circ }$

Q.

Name two factors which affect the critical angle for a given pair of media. State how do the factors affect it.

Q.

What is the smallest possible angle of incidence?

Q.

Two plane mirrors are initially inclined at 30° to each other and they move apart with an addition of 30° till the angle becomes 120°. The object is in between and equidistant from the mirrors. Find the sum of all the images formed. (Mirrors are inclined symmetrically).

1. 20

2. 21

3. 22

4. 23

Q.

A light ray is incident from a denser medium on the boundary separating it from a rarer medium at an angle of incidence equal to the critical angle. What is the angle of refraction for the ray?

Q. What will be the angle of refraction when the refracted ray passes along the surface of water or any other denser medium ?

1. ${30}^{\circ }$
2. ${90}^{\circ }$
3. ${45}^{\circ }$
4. ${60}^{\circ }$

Q.

State whether the following statement is true or false.
If the angle of incidence is greater than the critical angle, light is not refracted at all, when it falls on the surface from a denser medium to a rarer medium.

Q.

Diamonds sparkle more than glass because they have:

1. smaller critical angle than the glass

2. larger critical angle than the glass

3. critical angle plays no role

4. none of these

Q.

Consider a light ray travelling from a denser medium to air. The refractive index of the medium is $\sqrt{3}$. Calculate the angle of incidence, such that if it is further increased, total internal reflection will occur at the denser medium.

1. None of the above

2. $si{n}^{-1}\left(\frac{1}{\sqrt{3}}\right)$

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

4. $si{n}^{-1}\left(\frac{1}{\sqrt{5}}\right)$