REFRACTION OF LIGHT

Refraction is the bending of light when it passes from a medium to another medium. Light is refracted because its speed changes when it enters another medium (Huygen’s principle).

3

2

1

B

a paved road a stony road

In a paved road, person A and B move fast with the same speed. They are vertically connected. The arrow which is the normal (the perpendicular direction with respect to the line connecting A and B) points to the horizontal. As soon as A enters a stony road, his speed gets slower while the speed of B which is still on the paved road is fast. So in the same time, A travels less distance than that of B. Look at the condition 1 and 2. As soon as B enters the stony road, his speed also gets slower. The speed of B is the same as A now. So now in the same time, they travel in the same distance. Look at the condition 2 and 3. But now, the arrow does not point to the horizontal anymore. It is bent. This is Huygen’s principle. It explains that refraction happens because there is a speed difference between two mediums.