Geometrical Optics

Question 1

What is the definition of the normal?

Answer 1

An imaginary line perpendicular to a surface.

Question 2

How are the angles of incidence and reflection measured?

Answer 2

Angle of incidence: Measured between the incident ray and the surface normal
Angle of reflection: Measured between the reflected ray and the surface normal.

Question 3

What does the law of reflection state about the angle of incidence and the angle of reflection?

Answer 3

Angle of reflection = angle of incidence

Question 4

What is the speed of light in vacuum?

Answer 4

3 x 10^8 m/s

Question 5

What is meant by the refractive index of a material?

Answer 5

Ratio of speed of light in a vacuum to its speed in the material.

Question 6

What is the angle of refraction?

Answer 6

The angle between the normal to a surface and the refracted light ray.

Question 7

What happens to a light ray when it moves from an optically dense medium to an optically less dense medium?

Answer 7

It bends towards the less optically dense medium

Question 8

What is meant by the critical angle?

Answer 8

Angle of incidence where the angle of refraction is 90 degrees.

Question 9

What are the two conditions for total internal reflection to occur?

Answer 9

1. The angle of incidence is greater than the critical angle.
2. Light is travelling from an optically dense medium to a less optically dense medium

Question 10

How do you calculate the critical angle?

Answer 10

In the Snell law equation, @1 = @c
and @2 = 90 degrees