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Graphic from dorling kindersley books website

D. Index of Refraction (n) – a comparison of speed of light in a substance to its speed in a vacuum

If a substance has an index of refraction of 2.00 it means light is twice as fast in a vacuum than it is in that medium

c = speed of light in a vacuum
(3.00 x 10⁸ m/s)

    v = speed of light in a medium

n_vacuum = 1.00  

    n_air ≈ 1.00  , v ≈ 3 x 10⁸ m/s

Which substance slows down light the most when light enters from air?

Diamond,

(highest (n) index of refraction)

least?

Water 

(smallest (n) index of refraction) 

Any device with a lens refracts light

Ex 1) Speed of light in alcohol?    

n = 1.36 (Reference Table)

    n = 1.36 = c/v

1.36 = (3.00 x 10⁸ m/s)/V     

3.00 x 10⁸ m/s = 1.36V

Mathematical relationship
between n & v?

n = c/v

Inverse

Refraction in Glass

The human eye refracts light

1. Prediction θ_ref from θ_in

a. Snell's Law

1 – incident medium

2 – refractive medium

Air/Lucite

n₁sinθ₁ = n₂sinθ₂

1.00 sin53 = (1.50) sinθ₂  

.798 = 1.50sinθ₂

θ₂ = 32⁰  

Using pins to trace the path of light
from air into glass and back into air

b. n and V

1 – incident medium
2 – refractive medium

c. n, λ

When light refracts it BENDS, CHANGES SPEED and WAVELENGTH
 

Larger Version

Refraction and Wavelength
Don Ion

Ex) What is the angle of incidence?, angle of refraction?

0 degrees, 0 degrees

Total Internal Reflection