Chapter 5: Light Energy

Question 1

Definition of refraction of light.

Answer 1

the change in direction of path of light when it passes from one optically transparent medium to another

Question 2

Definition of incident ray.

Answer 2

the ray of light falling on the surface of separation

Question 3

Definition of refracted ray.

Answer 3

the ray of light traveling in the changed direction after undergoing refraction

Question 4

Definition of normal.

Answer 4

the perpendicular drawn on the surface of separation, at the point where the incident ray strikes it, i.e. at the point of incidence

Question 5

Definition of angle of incidence.

Answer 5

the angle between the incident ray and the normal

Question 6

Definition of angle of refraction.

Answer 6

the angle between the refracted ray and the normal

Question 7

What are the 2 laws of the Snell’s laws?

Answer 7

1. The incident ray, the normal at the point of incidence, and refracted ray lie in the same plane.
2. For a given pair of media and given colour of light, the ratio of the sine of angle of incidence (i) to the sine of angle of refraction (r) is a constant.

Question 8

What are the 4 ways to represent the refractive index of a medium?

Answer 8

1. μ (mew)
2. sin i / sin r
3. speed of light in first medium / speed of light in second medium
4. real depth / apparent depth

Question 9

Define total internal reflection.

Answer 9

the complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle

Question 10

Define critical angle.

Answer 10

the angle of incidence beyond which rays of light passing through a denser medium to the surface of a less dense medium are no longer refracted but totally reflected