# Refraction

Card 1: What is refraction?

## Refraction

Refraction is the bending of light rays when they pass at an angle in or out of materials such as glass and water.

Card 2: Law of Refraction - The Snell's Law

## Law of Refraction - The Snell's Law

1. The incident and refracted rays are on opposite sides of the normal at the point of incidence, and all three lie in the same plane.
2. The value of (sin i)/(sin r) is constant for light passing from one given medium into another. This is known as Snell's law.
Card 3: What is refractive index?

## Refractive Index

The value of (sin i)/(sin r) is called the refractive index of the medium and it gives us an indication of its light-bending ability.

Example 1

Diagram above shows a ray of light moving from air toliquid A. Find the refractive index of the liquid A.

Angle of incident, i = 90o - 30o = 60o
Angle of refraction, r = 45o

Refractive index,

\begin{gathered}
n = \frac{{\sin i}}
{{\sin r}} \hfill \\
n = \frac{{\sin 60^o }}
{{\sin 45^o }} = 1.22 \hfill \\
\end{gathered} 

Card 4: Define Refractive index.

## Definition of refractive index

Refractive index of a medium can be defined as the ratio of the speed of refracted light in vacuum to its speed in the medium.

Card 5: What is real depth and apparent depth?

## Real Depth and Apparent Depth

The real depth of an object is the vertical distance of the object from the surface of the liquid.

The apparent depth of an object is the vertical distance of the image of the object from the surface of the liquid.

Card 6: Give the equation of refractive index in terms of real depth and apparent depth

## Refractive index in terms of real depth andapparent depth:

Card 7: Refraction - From Less dense medium to Denser Medium

## Refraction - From Less dense medium to Denser Medium

Light passing into an optically more dense medium is bent towards the normal

Card 8: Refraction - From Denser Medium to Less dense medium

## Refraction - From Denser Medium to Less dense medium

Light passing into an optically less dense medium is bent away from the normal.

Card 9: Refraction - Along the Normal

## Refraction - Along the Normal

When the ray is perpendicular to the refraction plane, it will not be refracted.

Card 10: Name 3 natural phenomena due to refraction of light

## Phenomena Due to Refraction

1. Swingming pool appears shallower than its actual depth.
2. A spoon looked bent in a glass filled with water.
3. Twinkling of star.
4. The setting sun look oval in shape.