Simple Applications of Refraction of Light

Question 1

When does an object appear to be at a depth lesser than its real depth?

Answer 1

When it is placed in a denser medium and viewed from a rarer medium, because of refraction of light

Question 2

What is the formula for apparent depth?

Answer 2

Apparent depth = real depth/μ of medium w.r.t air

μ of medium w.r.t air = 1/ μ of air w.r.t medium

Question 3

What is the formula for shift?

Answer 3

Shift = real depth * (1 - 1/ a μ m)

Question 4

What does the shift by which the object appears to be raised depend on?

Answer 4

1. the refractive index of the medium
2. the thickness of the denser medium
3. the color (or wavelength) of incident light

Question 5

How does the shift depend on μ of medium?

Answer 5

Higher the μ of the medium, more is the shift

Question 6

How does the shift depend on thickness of medium?

Answer 6

Thicker the medium, more is the shift

Question 7

How does the shift depend on wavelength of color of light?

Answer 7

The shift decreases with the increase in wavelength of the light used

Question 8

For which color is the shift most and least?

Answer 8

It is more for violet light than for red light in any given medium

Question 9

Why does a fish when seen from air appear to be nearer to the surface of water than at its actual depth?

Answer 9

For water, a μ w = 4/3, therefore the depth of a water pond appears 3/4th of its original depth on seeing it from air in a nearly vertical direction

Question 10

What does an object placed in a rarer medium appear as when viewed from a denser medium?

Answer 10

It appears to be at a greater distance than its real distance

Question 11

Name the common phenomena that occur due to refraction of light

Answer 11

1. Twinkling of stars
2. Sun is seen a few minutes before it rises above the horizon in the morning while in the evening, a few minutes after it sets
3. A coin in a vessel is not seen when viewed from just below the edge of the vessel, but can be viewed from same position when water is poured into it
4. The print on paper appears to be raised when a glass slab is placed over it
5. A piece of paper stuck at the bottom of a glass slab appears to be raised when seen from above
6. A water tank appears shallower than its actual depth
7. A person’s legs as seen from outside appear to be short when standing in a pool