# Snell's Law Calculator

## Introduction

Snell's law makes it possible to calculate the angle of refraction of light passing from one medium to another.      n1 Â· sinθ1 = n2 Â· sinθ2

## Calculator

 Refractive Index 1 (n1): Refractive Index 2 (n2): Angle 1 (θ 1):

RESULTS:

 Angle 2 (θ 2): Critical Angle (θc): Speed (v1): km/s Speed (v2): km/s

## Clarifications

A easy way of see the behaviour of this law is to think that the ray in the medium with the higher refractive index forms a more perpendicular angle to the surface.

### Critical Angle

When n2 < n1, the ray in medium 2 forms a smaller angle with respect to the surface than in medium 1. For a given angle θ1, which we call the critical angle or limit angle, the angle θ2 is 90Âº. For angles θ1 greater than this value, the light can no longer escape from medium 1. The critical angle can be calculated from the following equation, which is derived from Snell's law:
θc = arcsin (n2/n1)

### Speed of light

When the ray passes from one medium to another, its frequency does not change. However, its wavelength and its propagation speed do change. These parameters are related by the following equation:
λ = v / f

. Knowing that the speed of light in a vacuum (c) is 299,792.458 km/s we can calculate the speed of light (v) in another medium with known refractive index (n) by refractive index (n) using the following formula:
v = c/n

## Some refractive indices

 Air: 1.000293 Carbon Dioxide: 1.000449 Hydrogen: 1.000132 Methane: 1.000444 Nitrogen: 1.000298 Oxygen: 1.000271 Milk: 1.35 Olive Oil: 1.47 Water: 1.333 Glass: 1.5 a 1.62 Diamond: 2.417 Polycarbonate: 1.59