Which standard unit is used to express frequency?

Answer 1

The SI unit for frequency is the Hertz. It is abbreviated as Hz and is defined as one cycle per second.
The unit is Hertz (Hz) and is defined as the number of cycles per second.
Frequency is measured in Cyles per Second which also has the official name of HERTZ
The basic unit is the hertz which means cycles per second. For more rapidly vibrating objects we often use megahertz, meaning millions of cycles per second.
The SI unit for frequency is "Hertz" or "reciprocal seconds" (1/s or s^-1). In other words a frequency is any measure of an action happening per unit time. It is basically an inverse measurement of time (how "frequent" something happens). The action happening varies. In sound waves the frequency determines how many crests of a sound wave pass by per second which derives it's pitch (in fact any frequency of a wave is found through the velocity divided by wavelength). Other actions can include the frequency of tempo in beats per minute (bpm) or the frequency of a engine in cycles per second (cps) or rotations per minute (rpm).

So the standard unit for frequency is any action happening per unit time. Common examples include bpm, rpm, cps. The list continues.