Optical Density

Q. Light travels the slowest in which of the following media?

1. Vacuum
2. Glass
3. Water
4. Air

Q.

Find the speed of light in diamond if it's refractive index is 2.5

Q.

The refractive index of kerosene is 1.44. Find the speed of light in kerosene.

Q. The refractive index of a denser medium with respect to a rarer medium is_______.

1. Less than one
2. 0
3. Greater than one
4. 1

Q.

1.The speed of light in a transparent medium is 1.8×10^8m/s. Find the refractive index of that medium.

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Q.

Which medium has the highest optical density?

1. Vacuum

2. Water

3. Glass

4. Air

Q.

Water is optically denser than glass.

1. True

2. False

Q.

What is refraction? Define refractive index.

Q.

How does the speed of light determine the optical density of a medium ?

Q. Absolute refractive index of any medium is always_______.

1. 1
2. 0
3. >1
4. <1

Q.

Write True or false for each statement :

(a) Water is optically denser than glass.

(b) A ray of light when passes from glass to air, bends towards the normal.

(c) The speed of light is more in glass than in water.

(d) The depth of a pond when seen from above appears to be less.

(e) Light travels at a lower speed in water than in air.

(f) Light travels in the same straight line path while passing through different media.

(g) The angle formed between the normal and the refracted ray is known as the angle of incidence.

(h) At the point of incidence, a line drawn at right angles to the surface, separating the two media, is called the normal.

(i) Image is formed by a mirror due to refraction of light.

(j) Rays of light incident parallel to the principal axis pass through the focus after reflection from a concave mirror.

(k) A convex mirror is used as a shaving mirror.

(l) The focal length of a convex mirror is equal to its adius of curvature.

(m) A concave mirror converges the light rays, but a convex mirror diverges them.

(n) A virtual image formed by a spherical mirror is always erect and situated behind the mirror.

Ans. True - (d), (e), (h), (j), (m), (n),

False - (a), (b), (c), (f), (g), (i), (k), (l)

Q.

What is apparent depth

Q.

Refractive index of water is ___ than/to that of air.

Q.

Give reasons:

Refractive index of a medium with respect to air can never be less than 1

Q. When light passes from medium 1 to medium 2, the refractive index of medium 2 with respect to medium 1 is called as___.

1. Absolute refractive index
2. Relative refractive index
3. Refraction
4. Reflection

Q.

Which is optically denser : water or air ? Give reason.

Q.

Out of air and glass, which is optically rarer ? Give reason.

Q.

What do you mean by this statement :

The refractive index of ice is 1.3

Q. Identify the denser medium in the given figure:

1. 
2. 
3. 

Q.

P, Q, R, and S are four media. They are arranged according to the speed of light in them as:
Q>P>S>R
Which medium has the least optical density?

1. S

2. R

3. P

4. Q

Q.

If a light ray from air enters three different media in such a way that the refracted angles are ${45}^0$, ${30}^0$ and ${60}^0$ respectively, then which is the densest medium among the three?

In the figure, $n_1$ represents refractive index of air.

1. Medium 1

2. Medium 2

3. Medium 3

4. Air is the denser medium

Q.

When light enters normally into turpentine oil from water, its speed ___ .

Q.

When a beam of light moves from a rarer medium to a denser medium:

1. It goes undeviated

2. It bends towards the normal

3. It bends away from the normal

4. It bends at 90^o

Q.

The speed of light in vacuum is:

1. $2\times {10}^{8}m/s$

2. $1\times {10}^{8}m/s$

3. $3\times {10}^{7}m/s$

4. $3\times {10}^{8}m/s$

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

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

Q. If a light ray from air enters three different media in such a way that the refracted angles are ${45}^0$, ${30}^0$ and ${60}^0$ respectively, then which is the densest medium among the three?

In the figure, $n_1$ represents the refractive index of air.

1. Medium 1
2. Medium 2
3. Medium 3
4. Air is the denser than the other given media.

Q.

If the refractive index of two media are equal, then

1. It will bend away from the normal.

2. Light will reflect in the same medium

3. Interface will absorb the light

4. No refraction will occur.

Q. "Value of refractive index remains same for light rays with different wavelength and for a particular material"

1. True
2. False

Q.

Choose the denser medium from the given figure:

1. Data insufficient
2. Medium 1
3. Medium 2
4. Both media have same refractive indices

Q. The angle of refraction, when a light ray approaches a glass-air interface from the glass side at the critical angle, will be :

1. ${45}^o$
2. ${90}^o$
3. equal to the angle of incidence
4. $0^o$