# Vibration level

The **vibration level** is in the vibration theory , the level of vibration .

- In mathematics and mechanics , this is the plane in which a pendulum swings. The movement of the pendulum spans the plane.
- In electrodynamics , the plane of oscillation of an electromagnetic wave is the plane in which the wave can oscillate; it is
*transverse*to the direction of propagation .

In general, the plane of vibration of a transverse wave is the plane that is perpendicular to the direction of propagation.

Polarization of a wave can only happen in the oscillation plane , which is why only transverse waves can be polarized. Longitudinal waves , such as sound , on the other hand, have no oscillation plane and are therefore not polarizable.