In the rotation speed measurement by a stroboscope when a st

In the rotation speed measurement by a stroboscope, when a stabilized mark is shown, does the corresponding stroboscope frequency in lighting have to be the same as the rotation speed? Why?

Solution

A stabilized mark in a stroboscope does not necessarily mean that stroboscope frequency and the rotational frequency are same. For a rotation speed, we can have a number of strobe light frequency for which stabilized mark is achieved. If the stroboscope lighting frequency is same or a multiple of the rotational speed, the rotating object will appear to be stabilized.