Question

What does wave refraction cause?

Answer 1

Generally, a change in both wavelength and velocity of the wave.

Explanation:

If we look at the wave equation we can get an algebraic understanding of it: `v = f xx lambda` where `lambda` is the wavelength. Clearly if v alters, either f or `lambda` must change. As the frequency is determined by the source of the waves, it remains constant. Due to conservation of momentum the direction alters (provided the waves are not at `90^@`)

Another way of understanding this is to consider the crests as being lines of soldiers - an analogy I’ve use during many times. The soldiers are marching at an angle (say `45^@`) from the concrete parade ground onto,the grass lawn. As they move onto the lawn each soldier slows down, this means the distance between those slower soldiers is reduced.

Look at the diagram below (imagining the wave crests as the soldiers) and you’ll see that because velocity falls, the wavelength changes too (and the direction of travel.) That means frequency must remain constant -