What is a periodic change??

It is a change which occurs repeatedly in same interval of time.Example-pendulam, hands of a clock.

when an object repeat themselves movement  at reggular  interval of time it is said to have periodic change.eg rotation of earth , revolution of earth,motin of swing,movement of pendulam etc.

the change which repeat it self at regular interval of time it is said to have periodic motion .eg motion of swing ,formation of day and night  etc.

Periodic can be reffered to any thing which repeats after a constant interval of time.

Ex: Movement of clock., Movement of pendulum of a wall clock.

 a change that repeats itself ater fixed intervals of time is called a periodic change.eg day and night