Nu is the symbol of frequency used in science. Frequency is also a property of electromagnetic wave and is defined as number of complete cycles per second. Hence its SI unit is HERTZ. Dimensional formula is given as[M ⁰ L ^-1 T ⁰ ]OR T ^-1 . In Sound energy, Frequency denotes the pitch of any wave/sound. That is, how much shrill or sharp the voice is.