Final answer:
A periodic signal repeats itself at regular time intervals. The period of a signal refers to the time it takes for one complete oscillation to occur, while the frequency is the number of oscillations per unit time. The frequency and period are inversely related (frequency = 1/period).
Step-by-step explanation:
A continuous-time signal is said to be periodic with a period T if x(t) = x(t + T). In the context of periodic motion, such as the oscillation of a guitar string or an object on a spring, the period refers to the time it takes for one complete oscillation to occur. It is the time interval between two consecutive identical positions in the motion. The frequency, on the other hand, is the number of oscillations per unit time and is the reciprocal of the period (f = 1/T). For example, if a guitar string completes one oscillation every 0.1 seconds, its period is 0.1 seconds and its frequency is 1/0.1 = 10 Hz.