Refraction of light Flashcards
What is refraction?
Refraction is when light moves from one material (medium) to another and changes speed.
On a ray diagram, what do we call the imaginary line which is at right angles to the boundary between one medium and another?
The normal.
NB All angles are measured from this line.
What is the name of the angle the incident ray makes with the normal?
The angle of incidence.
What is the name of the angle the refracted ray makes with the normal?
The angle of refraction.
What happens to a ray of light when travelling from air to glass, in relation to the normal?
The ray bends towards the normal on moving from a less dense material (air) to a more dense material (glass).
What happens to a ray of light when travelling from glass to air, in relation to the normal?
The ray bends away from the normal on moving from a dense material (glass) to a less dense material (air).
NB the ray leaving the block is parallel to the ray entering the block.
What alway happens to a ray of light when it moves from one medium to another?
It always changes speed.
What happens to a ray of light when the incident ray is at 90° to the boundary between the 2 mediums (i.e parallel to the normal)?
The ray of light changes speed but does not change direction.
NB This condition prevents us from defining refraction as the bending of light.
What happens to the speed of light when it moves from air to water?
It slows down as water is more dense than air.
What happens to the frequency of light in refraction?
The frequency does not change in refraction as this is set by the source (whatever is producing the light).
What happens to the wavelength of light in refraction
The wavelength in refraction does change.
If the speed of light decreases, the wavelength of the light decreases. If the speed of light increases, the wavelength of the light increases.
NB This is true because v = f 𝝺 and the frequency is unchanged.
