Frequency is the number of waves that pass a fixed point in
unit time ; also the number of cycles or vibrations undergone during one unit
of time by a body in periodic motion . A
body in periodic motion is said to have undergone one cycle or one vibration
after passing through a series of events or positions and returning to its
original state.Thus the trough is the highest point reached by the frequency in transmission of frequencies .
It is used in transmission of electric frequencies thus
enhance communication as vibration of the same frequencies of the same resonate together.