Critical Angle

Question 1

What is critical angle ?

Answer 1

Critical angle is a fixed angle for each medium

Question 2

Whenever the second medium is optically less dense, the refracted ray could……

Answer 2

1. Go to the second medium
2. Slide on its boundary
3. Reflect back into the first medium

Question 3

Those 3 situations depends on the relation between …..

Answer 3

Angle of incidence and critical angle

Question 4

When does the first situation happen?

Answer 4

When the angle of incidence is less than the critical angle, the refracted ray moves further away from the normal line

Question 5

When does the second situation happen? And what is the angle of refraction?

Answer 5

When the angle of incidence is the same as the critical angle, the refracted ray slides on the boundary.
For this situation, the refraction angle is 90*, then Sin r = 1 always

Question 6

When does the third situation happen? And what is this situation called? And how are the angles?

Answer 6

When the angle of incidence is bigger than the critical angle, the refracted ray reflects back into the first medium.
This situation is called Total internal reflection, and the angle of incidence is the same as the angle of refraction i = r

Question 7

What is the formula to find the critical angle?

Answer 7

Sin (critical angle) = N2/ N1