💯 Definition of "REFRACTIVE INDEX" Explained with Clear Examples #1

Опубликовано: 03 Ноябрь 2021
на канале: iitutor.com

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 define refractive index in terms of changes in the velocity of a wave in passing from one medium to another
 present information using ray diagrams to show the path of waves reflected from:
– plane surfaces
– concave surfaces
– convex surface
– the ionosphere

The Snell’s law:

Before the nature of light was properly understood, the refraction of light was discussed in terms of the refractive index of a material. It was later discovered that the refractive index was related to the speed of light in the material.

Snell's Law relates the change of velocity to the angle of incidence and the angle of refraction:
The refractive index of a material is a measure of how much it bends light.
It is also a measure of how fast light travels in the material.
The refractive index of a material can be calculated by measuring angles.

Angles and Speeds
The angle of incidence (from the normal to the incoming ray) is represented by i. The angle of refraction (from the normal to the refracted ray) is represented by r.
The relation between speed and the angles is given by sin(i)/sin(r) = v1/v2

Snell's law
We assign a refractive index, n, to the material by measuring the speed of light through it.
sin(i)/sin(r) = v1/v2
This is called Snell’s Law.

Refraction through Water
Air’s refractive index is n1 = 1. Water’s is n2 = 1.33.
When air passes into the water at an angle of incidence i, we can use Snell’s law to predict the angle of refraction: r = sin^-1 (1/1.33 sin(I))

Different Materials
Different substances have different refractive indices. Remember that in general, light travels more slowly through dense substances. This means that denser substances have larger refractive indices.

Different Refractive Indices
Medium Refractive Index
Air 1.00
Ice 1.31
Water 1.33
Ethanol 1.36
Fused quartz 1.46
Perspex 1.49
Crown glass 1.53
Flint glass 1.61
Zircon 2.16
Diamond 2.41

0:00 Introduction
0:03 2.4.3.1 Refractive Index
1:16 Angles and Speeds
3:04 Snell's Law
5:02 Refraction through Water
6:46 Different Materials
7:40 Different Refractive Indices Medium