Webster's dictionary defines a wave as "a disturbance or variation that transfers energy progressively from point to point in a medium and that may take the form of an elastic deformation or of a variation of pressure, electric or magnetic intensity, electric potential, or temperature."

The most important part of this definition is that a wave is a disturbance or variation which travels through a medium. The medium through which the wave travels may experience some local oscillations as the wave passes, but the particles in the medium to not travel with the wave. The disturbance may take any of a number of shapes, from a finite width pulse to an infinitely long sine wave.

Frequency: Frequency refers to how many waves are made per time interval. This is usually described as how many waves are made per second, or as cycles per second.

Hertz is a unit of frequency (of change in state or cycle in a sound wave, alternating current, or other cyclical waveform) of one cycle per second. It replaces the earlier term of "cycle per second (cps)." Even though a Hertz is a per second, which would seem to me to be a base unit (because a second is a base unit). It's not considered a base unit because a hertz is CYCLE / SECONDS which means in order to "measure" a hertz you would need to count (measure) the number of cycles and and time, and thats why it's not a base unit

Example: Three waves are plotted for one second in the diagram above, each wave has a different frequency.

The upper most plot shows a wave with a frequency of 20 Hz, It completes 20 full cycles in one second, 20 cycles / 1 sec = 20 Hz

The middle plot shows a wave with a frequency of 40 Hz, it completes 40 full cycles in one second, 40 cycles / 1 sec = 40 Hz

The bottom plot shows a wave of 80 Hz.

**Period:** Period refers to the time which it takes to do something. When an event occurs repeatedly, then we say that the event is **periodic** and refer to the time for the event to repeat itself as the period.

The Frequency Period Connection. Frequency is offend refereed to as the number of events that happens in a given time.** Frequency simplified is simple cycles / Sec. ** Period on the other hand is the amount of time it takes for a single event. **Period simplified is sec / cycle. **

** ** So the relationship between them is **Frequency = 1 / Period **

Example: Three waves are plotted for one second in the diagram above, each wave has a different frequency.

The upper most plot shows a wave with a frequency of 20 Hz, It completes 20 full cycles in one second, 20 cycles / 1 sec = 20 Hz. The period is 1/20 sec, It takes 1/20 th of a second for that event to happen again

The middle plot shows a wave with a frequency of 40 Hz, it completes 40 full cycles in one second, 40 cycles / 1 sec = 40 Hz. The period is 1/40 sec, it takes only 1/40 th of a second for that event to happen again

The bottom plot shows a wave of 80 Hz. The period is 1/80 sec.