In Vibration Analysis 'Beat' Frequency Is

Multiple Choice

In vibration analysis 'Beat' frequency is

A) The frequency at which vibrations of a system are damped
B) Said to occur when two vibrations of almost equal frequency are present
C) The frequency when a system exceeds the vibrations frequency from the critical value
D) The frequency below which vibrations do not cause appreciable damage to equipment
E) One at which the vibrations of a system act exactly opposite to the other thereby causing damping