2.2 - Refraction

Snell’s Law equation

n = sini / sinr = c1 / c2

Conclusion to experiment to verify snell’s law

when light passes from transparent medium to another of different optical density, ratio of sine of incidence angle/refraction constant

Inverse equation

2n1 = 1/1n2

Absolute refractive index

refractive index of medium relative to vacuum

Absolute values equation

1n2 = n2/n1

When I<c

light refracts away, weak internal reflection

When I=c

at crit angle angle of refraction is 90*, strong internal reflection

When I>c

all light reflected back

Crit angle equation

sinc = 1/aNg

How to find crit angle of glass

increase incidence angle until TIR just occurs

Uses of TIR

optical fibres

What are optical fibres and what happens at where does TIR occur?

pure glass core with less dense glass/plastic cladding. TIR occurs at core/cladding boundary

Where does TIR occur?

only at boundary of 2 media, where light comes from more optically dense medium

What is structure and use of flexible endoscope in medicine?

allows us to look in body. Illumination bundle that lights and image bundle carrying back reflected light

How are optical fibres arranged in image bundle?

coherent