Topic 3 - Refractive Index

Question 1

what is the refractive index of a material?

Answer 1

how fast light transfers into that material

Question 2

what is the equation for refractive index?

Answer 2

speed of light in a vaccum (c) / speed of light in that material (v)

Question 3

what is snells law?

Answer 3

refractive index = sin (angle of incidence) / sin (angle of refraction)

Question 4

what happens if you increase angle of incidence?

Answer 4

angle of refraction gets closer and closer to 90

Question 5

what is the critical angle?

Answer 5

the angle of incidence when angle of refraction = 90

Question 6

what happens when you increase past critical angle?

Answer 6

you get total internal reflection, no light leaves the medium.

Question 7

what is the equation for critical angle?

Answer 7

sin (critical angle) = 1 / refractive index

Question 8

how do optical fibres work?

Answer 8

the core of the fibre is so narrow that light signals passing through it always hit the boundry at angles higher than C, so light is always totally internally reflected

Question 9

how do periscopes work?

Answer 9

a ray of light travels into one prism where its totally internally reflected by 90 degrees
this then happens again to a lower down prism
the ray is now travelling parallel to its inital path but at a different height