Cycle vs Period
Cycle and period are two important terms that are widely used in almost all fields, in physics. These topics are very important in the study of the wave theory. The ideas about cycle and period are not only used in physics but also used in many other fields such as astronomy, mathematics, music and even some aspects of physiology. The terms, cycle and period, take different meanings upon where they are applied, but here we discuss these topics related to physics only. In this article, we are going to discuss what cycle and period are, the definitions of the cycle and period, their similarities, and finally the difference between cycle and period.
What is Cycle?
A cycle is a complete session (or an event) of a sequence of repeating events. A process in which cycles are created, is called a cyclic process. The heartbeat of human beings is a familiar example for a cyclic process. A cardiac cycle occurs from the beginning of one heartbeat to the beginning of the next. If we think about a simple sinusoidal wave, a single cycle is completed by the fraction inbetween two consequent peaks of that wave. Cycle is a concept of wave motion, and it provides a way to represent wave motion in pictorial form. In uniform circular motion, one cycle is defined as the complete path along circumference.
What is Period?
Period is a very important concept in the study of fields such as wave motion, optics, acoustics and telecommunication. To understand what period is one should have a proper understanding about frequency. Frequency is defined as the number of cycles per unit time. The SI unit for frequency is hertz (Hz), here 1 Hz means that one cycle repeats once per second. Now it is easy to understand the concept of period. Period is the time taken by one cycle. The relationship between period and frequency is that period is the reciprocal of frequency. This relationship can be represented mathematically as T=1/f, where period denoted by T, and frequency denoted by f. It seems that SI unit for the period is the second. If you think about a simple sinusoidal wave, which is plotted for displacement vs time, period of the wave can be represented as the length between two consequent peaks along the time axis. If we think about the angular motion, period is given by the equation T=2π/ω, where period denoted by T, and angular frequency denoted by ω. In angular motion, period is also measured in seconds.
What is the difference between Cycle and Period ? • Cycle is a concept of wave motion. It does not have units and dimensions, but the period is a scalar quantity. The SI unit of the period is the second, and its dimension is [T]. • There is a direct relationship between the period and the frequency. Period is inversely proportional to the frequency, but there is no such direct relationship between cycle and period. • Cycles of some waves can be seen, but period cannot be seen. • The instruments such as stop watches, clocks are used to measure the period, but we do not have instrument to measure cycles. • Sometimes the shape of the cycle can be changed with time, but period does not change with time. This occurs in damped vibrations.

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