Period and Frequency

Figure 94.

PERIOD AND FREQUENCY

In looking at the displacement of a guitar string, there will be a steady sound for a period of time. The vibration of the string takes the same time for each vibration over a period of time. Periodic motion is motion that repeats itself at regular time intervals. The time it takes for a single oscillation is constant and is called the “period”, called by the letter T. The SI units are that of seconds but it could represent any period that makes sense. Periodic motion is, by definition, repetitive motion.

The frequency is not the same thing as the period. If something has a period of 0.5 seconds, its frequency will be 2 cycles per second so that the frequency is the inverse of the period. The SI unit for the frequency is in Hertz, which is the same thing as a cycle per second. Vibrations can be singular or multiple but oscillations are defined as being repetitive over several cycles.