Refraction – wave fronts
The following diagram shows the
refraction of a plane wave at a plane interface. The position of the refracted wave is
formed using the idea of secondary wavelets.
One side of the wave moves from A
to C (a distance v
gt) in glass in the same time that the other side of the
wavefront moves from B to D (a distance v
at) in the same time in air. The wave
front recombines at CD.
The angle of incidence in air is
qa and the angle of refraction in glass is
qg.
sin
qa =
v
at/AD and sin
qg =
v
gt/AD
Therefore sin
qa/ sin
qg = v
at/v
gt =
v
a/v
g = n and this is Snell's law of refraction.
schoolphysics plane wave refraction animation
To see an animation of the refraction of plane waves click on the animation link.
A VERSION IN WORD IS AVAILABLE ON THE SCHOOLPHYSICS USB
