Internal Reflection

Question 1

what is internal reflection

Answer 1

1) light speeds up when entering a less optically dense medium.
2) When this happens, some light is refracted and some light is reflected.

Question 2

when will light travel along the boundaries of two mediums

Answer 2

If the angle of incidence is the same as the critical angle

Question 3

when does total internal reflection occur

Answer 3

If the angle of incidence exceeds the critical angle

Question 4

What happens when the critical angle of incidence is exceeded?

Answer 4

all the light is reflected

Question 5

how do optical fibres transmit light

Answer 5

by total internal reflection

Question 6

what happens/is there in cladding

Answer 6

1) each fibre has a core of optically dense material that is covered by a layer of cladding with a much lower optical density.
2) This means that the boundary between the two materials has a very small critical angle.

Question 7

how is light transmitted over very long distances

Answer 7

Most of the light will be totally internally reflected and continue to travel through the core.

Question 8

in small critical angles what light will cross the boundary and be reflected

Answer 8

Only light approaching the boundary at an angle that is very close to the normal (90 degrees to the boundary) will cross the boundary and be refracted (this light is lost).

Question 9

what are the important parts of an optic fibre

Answer 9

1) Core
2) Cladding
3) Protective coating

Question 10

how do optical fibres transmit light

Answer 10

by total internal reflection

Question 11

What are the conditions for total internal reflection?

Answer 11

1) the critical angle Is exceeded

2) the medium is entering a substance with a lower optical density