Sine Waves

Let me explain what is meant by waves,

A wave is an oscillation which moves in space, such as sound waves, earthquake waves and the matter waves and light waves which turn out to make up just about everything in the universe. Sine waves turn up all over the place; more complex waveforms can always be broken down into a series of superimposed sine waves of various frequencies, in a process known as a Fourier transform. Sub-atomic 'particles' are best thought of as wave packets.

This extremely general applicability of the idea of sine waves results in trigonometric functions turning up everywhere you look in physics. The most general form of the basic wave equation, appearing everywhere from classical mechanics through electromagnetism to quantum physics, is this:

x = A × cos (ω × t + d / λ)

where λ is the wavelength (the distance between one peak of the wave and the next) and d is the distance along the wave. A full exposition of the mathematics of waves is beyond the scope of this writeup; I will just mention quickly that a fuller understanding of it requires a grasp of the idea of superposition and interference - what happens when waves meet each other; refraction - what happens when a wave passes from one medium to another; and diffraction - what happens when a wave passes through a hole. Standing waves and resonance are also profoundly important almost everywhere that waves turn up; they account for the sounds made by different objects, the energies of photon emitted by different atoms and molecules, and for a staggeringly wide range of other phenomena.

Hope the above explanation helped you..