Which way will light bend if it encounters a medium through which it it travels faster? What if it travels more slowly?
1 Answer
away from/towards the normal
Explanation:
when light travels from one medium to another, it is refracted, meaning that its angle and speed change.
light travels faster through less dense media, and slower through denser media.
e.g. when going from glass to air, it travels faster.
it also bends away from the normal.
the normal is an angle
(the normal is often drawn as a dashed line, according to convention.)
in the image, the angles outlined are different sizes; the angle between the normal and the wave in air is larger than the angle between the normal and the wave in glass.
the angle between the ray in glass and the normal is the angle of incidence.
the angle between the ray in air and the normal is the angle of refraction.
this means that when light travels from glass into air, the refracted ray is bent further away from the normal.
the opposite is true when light travels into denser media:
in the image, the angle between the normal and the wave in air is larger than the angle between the normal and the wave in glass.
the angle of incidence is larger than the angle of refraction - this means that the light ray in glass is refracted closer to the normal.
in summary:
when light travels faster, it bends away from the normal, since it is entering a less dense medium.
when light travels slower, it bends towards the normal, since it is entering a denser medium.
