Light Refraction – the “bending” of light as it passes through a surface from one medium to another When light leaves a less dense media such as air and enters a more dense media such as water, the light will bend towards the normal When light leaves a more dense media such as water and enters a less dense media such as air the light will bend away from the normal

i – called the angle of incidence r – called the angle of refraction Dotted line – Imaginary called the normal Air – less dense than water i r Water The ray of light bends towards the normal i – called the angle of incidence r – called the angle of refraction This happens for example when a straw is put into a glass of water, it looks bent

i r

When the sine of the angle of incidence is divided by the sine of the angle of refraction it gives the refractive index, n. this is called Snell’s law. Sin i =n Sin r