Refractive Index

Q.

What is the speed of light?

Q. What is the velocity of light in a medium having refractive index $1.5$?

1. $1\times {10}^{8}m{s}^{-1}$
2. $2\times {10}^{8}m{s}^{-1}$
3. $3\times {10}^{8}m{s}^{-1}$
4. $1.5\times {10}^{8}m{s}^{-1}$

Q.

In vacuum the speed of light depends upon

1. frequency

2. wavelength

3. velocity of light source

4. none of these

Q.

Light travels fastest in

1. Air

2. Water

3. Glass

4. Diamond

Q.

During the refraction of light, the frequency of light remains constant. Explain the reason.

Q.

In which medium the speed of light is maximum?

Q.

The refractive index of water and olive oil is $1.33$ and $1.46$ respectively. When light passes from water to olive oil, the light ray bends towards the normal.

1. True

2. False

Q.

Define the term refractive index of a medium in terms of velocity of light

Q.

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

1. 4000 Å

2. 6000 Å

3. 9000 Å

4. 15000 Å

Q.

What is the physical significance of refractive index?

1. It tells the density of the medium

2. It tells how faster the light is moving in that medium

3. It says how much air resistance the medium has

4. It doesn't have any significance

Q.

Why is the refractive index of atmosphere different at different altitudes?

1. Because air density changes with altitude

2. Because speed of light in vacuum changes.

3. The refractive index of atmosphere at different altitudes doesn't change.

4. Because of total internal reflection

Q. A fish in water(refractive index n) looks at a bird vertically above in the air. If y is the height of the bird and x is the depth of the fish from the surface, then the distance of the bird as estimated by the fish is?

Q.

A ray of light traveling in air falls on the surface of water. The angle of incidence is ${60}^0$ with the normal to the surface. The refractive index of water = $\frac{4}{3}$. Calculate the angle of refraction. [2 MARKS]

Q.

The law of reflection states that the angle of incidence is always _________to the angle of reflection.

Q.

Refractive index is always a constant.

1. False

2. True

Q.

If the refractive index of a medium is $1.25$, find the speed of light in this medium. Given the speed of light in air is $3\times {10}^{8}m/s$.

Q.

_______ occurs due to change in the speed of light when it enters an optical medium of different optical density.

Q.

What is the magnitude of the critical angle for (a) Water- Air interface and (b) Glass- Air interface?

Q.

When light enters from air to water, then its frequency

1. increases and speed decreases

2. is same

Q. A ray of light is incident on a set of media at an angle 60°. The angle of refraction is different for different media as shown.
In which medium the speed of light is slowest?

1. 1
2. 2
3. 3
4. Same in all

Q.

What is the unit of refractive index?

1. metre/second

2. metre

3. no unit

4. Dioptre

Q. As if the force is constantly increase there is increase in acceleration therefore increase in kinetic energy making velocity increase to infinity but it cannot go beyond velocity of light therefore mass increases to compensate the velocity but then how can blackhole form if any object cannot go beyond the speed of light?

Q.

Fill in the blanks with suitable words.

Water is optically denser than ____________ but optically rarer as compared to________________.

Q.

If the refractive index of medium A is higher than that of the medium B, then a ray of light going from B to A will

1. can’t calculate with the given data

2. pass through the normal

3. bend towards the normal

4. bend away from the normal

Q.

Which of these media has the highest refractive index?

1. Glass

2. Air

3. Diamond

4. water

Q.

How do you define the term refractive index of two media in terms of speed of light through them?

Q.
Based on their refractive index, sort the speed of light in ascending order.

1. Glass = 1.50
2. Diamond = 2.41
3. Water = 1.33
4. Kerosene = 1.41
5. Ruby = 1.76

Q.

What is the unit for representing refractive index?

1. $m/s$

2. $ms$

3. $m/s^2$

4. $Ithasnounit$.

Q. An irregular crystal structure reflects all the light that falls on it as shown in the diagram.

Which option best describes the picture?

1. Diffused reflection
2. Virtual image formation
3. Light source
4. Irregular reflection

Q. An object is placed at a distance of $150cm$ from a concave lens of focal length $120cm$. Find the nature of the image.

1. Erect and virtual
2. Real and invented
3. Erect and real
4. None