Transverse waves are waves which move particles in a direction perpendicular to the direction of a wave. An example of transverse waves are ocean waves in which water moves up and down, but does not move forward with the wave. The counterparts to transverse waves are longitudinal waves which move particles in the direction that the wave moves.
Let's talk about transverse waves, the word transverse means perpendicular so what on earth could I mean by a transverse wave? Well when you've got a wave it's got to move, remember that that's waves do. They move off of their own volition through a medium, so that takes up one direction when I call a wave transverse what I'm saying is that the disturbance that it represents takes place perpendicular to the direction in which it's moving. So we can for example consider a chain that we've got tied between 2 poles. And it's just sitting there and I decide to hit it right? So I hit it at one side and then the disturbance is going to propagate like that but the chain itself is moving back and forth in this way. So this and this are perpendicular to each other and that means that, that's a transverse wave.
Alright so let's just look at an example of a transverse wave, here we've got one. The equilibrium is the flat line and the wave is this guy right here. He's moving in this direction so clearly the disturbance is perpendicular, perpendicular alright now what I've seen a lot of problems ask along this topic is what direction will these different points move in as the wave propagates. So we could for example ask what's going to happen to point a as the wave moves through? Well the wave's moving in this direction, the easiest way to do problems like this is to just re-draw the wave. So it's moving in that direction, here we go that's what it's going to do right? So where did point a go? It went down, where did point b go? It went up, where did point c go? It went up right? Where did point d go? It went down. So that's really easy to do but it's not something that you may have thought of doing.
Alright so let's go ahead and look at why transverse waves are important, alright so we've got something called polarization. This comes up a huge amount in studies of light which we're not going to talk about right now but it is the property of transverse waves. The idea is that we live in 3 dimensions 3. The wave motion takes up one of them so how many are left over to be perpendicular to that? Well we got 2 left over, so that means that we have 2 independent transverse waves 2 of them. These 2 things are called polarizations and so you'll often see this in questions about whether or not a wave can be polarized. If it's transverse it can be polarized, if it's not transverse it can't be polarized. That's transverse waves.