A sine wave is a one which varies continiously in amplitude and also change the direction
It has positive and negative values
The set of positive/negative values or the change in one direction is called as an Alternation. Thus sine wave has two alternations. A positive alternation and a negative alternation
Cycle of a sine wave is one complete set of postive and negative values, these values repeat itself.
Period is the time taken for the sine wave to complete one cycle. It is measured in seconds, desinated as T
Frequency is defined as the number of cycles of sine wave in one second. Its unit is Hertz, designated as f
f=1/T