# Transverse waves

1. Oct 17, 2008

### GAGS

Hi all, i want to ask a simple question which is not so for me. Actually while studying transverse waves, a line is written:-"EACH TRANSVERSE WAVE HAS TWO POSSIBLE POLARISATION STATES". Can any body tell me please which are those two possible polarisation states refer here (either up and down or something else).Please help
Thanks

2. Oct 18, 2008

### Lojzek

The definition of transversal wave is that the deviation vector (or another vector quantity in a general case) is perpendicular to the line of wave propagation. Since our space is 3 dimensional, the set of all vectors perpendicular to a certain direction is 2 dimensional (a plane). Any vector in that plane can be expressed as a linear combination of 2 vectors, that are perpendicular to each other and the line of propagation: these are the 2 possible polarizations. For example: if the wave propagates in x direction, then the vector quantity lies in yz plane (if it is a transversal wave) so it can have a direction y or z (or a linear combination of them).

3. Oct 20, 2008

### billiards

The definition above is spot on. In seismology it was recognized by expansion of Newton's second law that by conservation of momentum, a disturbance in the strain of an elastic material will propagate a field of disturbance involoving two scalar potentials. One of these scalar potentials is involved with the divergence of the strain field and is manifest as a compressional wave, the other scalar potential relates to the curl of the strain field which is manifest as a transverse wave. Thus the transverse wave is an order higher than the compressional wave and can be decomposed into two components as opposed to the one which is sufficient to describe the directionality of compressionally induced particle momentum.