It has a natural resonant frequency at which it oscillates. The resonator generally oscillates in torsion or transversely (as a cantilever beam or tuning fork). The tip of the trichome oscillates like a pendulum. In radial direction, the diffraction intensity smoothly oscillates. Yet, because the down quark is massive, it oscillates and decays. Light also has a polarization, which is the direction in which the electric field oscillates. The geodesic oscillates about the equator. A platform shaker has a table board that oscillates horizontally. The function derived by Landau oscillates with high frequency. In localized surface plasmons, the electron cloud oscillates collectively. In the active hydrogen maser, the cavity oscillates by itself. These effects can be used to adjust the frequency at which a crystal oscillates. When a water parcel encounters a different density it oscillates and creates internal waves. When released, it oscillates again until it reverts to its rest state. Over a 41,000 year cycle, the tilt oscillates between 22.1 and 24.5 degrees.