# What happens to light if it enters a glass block along the normal?

## What happens to light if it enters a glass block along the normal?

If the light enters along the normal line i.e. perpendicular (at 90°) to the block then no refraction (change of direction) occurs. The light will be slowed down as it travels through the denser medium but it will NOT change direction.

## What happens to light when it goes from air into a glass block?

Light is refracted when it crosses the interface from air into glass in which it moves more slowly. Since the light speed changes at the interface, the wavelength of the light must change, too. The wavelength decreases as the light enters the medium and the light wave changes direction.

What happens when light passes through glass?

When light hits a glass object, some of the light bounces (or reflects) off the glass. The rest of the light keeps going through the glass object, but the light is bent (or refracted) as it moves from the air to the glass. The index of refraction for the oil is very close to the index of refraction for glass.

### Why light bends more when it passes through diamond than it does through glass?

The greater the refractive index the more the light refracts. Glass has a refractive index of 1.5, water 1.3 and diamond 2.42. This means that light will bend more when it hits a diamond than it will when it hits a piece of glass of the same shape. It is partly this that makes diamonds sparkle so much.

### How does refraction work in a glass block?

At the boundary between two transparent substances: the light slows down going into a denser substance, and the ray bends towards the normal the light speeds up going into a less dense substance, and the ray bends away from the normal The diagram shows how this works for light passing into, and then out of, a glass block.

Why does light bend when it enters glass?

Glass is denser than air, so the light from outside passes from a fast medium, through a slow medium and into a fast medium again. The light will take the path from outside to your eye that spends the least time You can also see that the rule from earlier still applies: when the light enters the glass the ray is bent towards the normal.

## What happens to the refraction of a ray of light?

Direction of bending When a ray of light passes from a less dense material (eg air) into a denser material (eg glass or water) it is bent away from the surface between the two materials. This means that in this situation the angle of refraction is always lessthan the angle of incidence.

## What happens to light waves when they pass through a glass block?

Light waves change speed when they pass across the boundary between two substances with a different density, such as air and glass. This causes them to change direction, an effect called refraction. The diagram shows how this works for light passing into, and then out of, a glass block. The same would happen for a Perspex block: