From studying waves I find that I can visualise longitudinal waves where the wave propagates in the direction of the displacement. However I don't understand what causes the propagation perpendicular to the displacement in transverse waves. How is a perpendicular displacement caused in adjacent particles?
1$\begingroup$ It is the Energy which propagates in the perpendicular direction. e.g. waves on a string, the adjacent particles pick the energy from those before them. $\endgroup$– user31782Apr 25, 2014 at 11:19
1$\begingroup$ en.wikipedia.org/wiki/Transverse_wave has an animation $\endgroup$– anna vApr 25, 2014 at 11:20
$\begingroup$ Why does the energy propagate in a direction perpendicular to the motion and why does the energy cause perpendicular motion in subsequent particles? $\endgroup$– HamzaApr 25, 2014 at 11:21
This transverse plane wave is illustrated here
If we go to a medium, the "points " will be the molecules which are adjacent. An organized impulse is set up as a function of time, pulling down the one on the right and transferring an impulse delta(p) in the longitudinal direction and then the next molecule pulls up and passes the impulse.
A longitudinal wave is what you get when you stretch and compress a slinky or spring. The slinky can stay inside the cylinder, but you can see it compressing and expanding. Sound is longitudinal.
A transverse wave is what you get when you wave the end of a piece of string up and down. The bits go up and down, but the waveform travels along the string. Light is transverse, as are ocean waves.