A wave is on a continuous cycle creating crests and troughs when oscillating. A wave completes a full cycle when it moves from one point to another, and returns to its starting position. So, when observing an oscillating wave, it will create a crest, then a trough, and finally begin to form another crest. A cycle can be clearly seen when marking a point on a wheel and watching it rotate from the front or rear. When the point is directly opposite from it's starting position, it has created half of a cycle. The point will have completed a full cycle once it returns to its starting position.
A vector has a magnitude and direction. For example, velocity, a type of vector, has a magnitude and a direction which work together to move an object from one place to another. When traveling, it's not enough to know the speed you also need to know what direction to travel. A scalar has only magnitude. Speed is a scalar. It has a magnitude, but no direction.
When applying force to an object this object begins to move repeatedly back and forth or up and down. When looking at a wave, we identify this type of behavior as being that of an oscillator, which means that it vibrates. An oscillator obeys the principle of Simple Harmonic Motion (SHM). A simple harmonic oscillator is an object either repeatedly swaying from side to side, such as a pendulum, or up and down, like a mass attached to a spring.
Click here to see a java applet of a Simple Harmonic Oscillator.
The wavelength is the total distance traveled by the wave in one full cycle. It is represented by the Greek letter lambda, . The period is amount of the amount of time it takes to complete one cycle. The frequency is the number of cycles the wave completes in a given time, and is the inverse of the period. The frequency times the wavelength is the velocity of the wave.
The amplitude of a wave is the maximum displacement from the equilibrium position, which is the point of zero displacement. There is a point of oscillation when the particle or object stops and is about to change directions. The distance between this point and the equilibrium point is the amplitude. When the wave reaches its maximum point, the velocity is zero, since it is neither rising nor descending.
The normal is an imaginary line drawn perpendicular to a surface. This is sometimes referred to as the surface normal.