When using a stroboscope, when does the display appear to show the object standing still?

The appearance of an object seemingly standing still when using a stroboscope is based on the principle of synchronization between the stroboscope's flashing frequency and the object's rotational speed. When the frequency of the stroboscope matches the object's revolutions per minute (RPM), the light emitted by the stroboscope illuminates the object at precise intervals in sync with its rotation. This synchronization creates the effect of the object appearing stationary, as each flash captures the object at the same point in its cycle.

In scenarios where the flashing frequency does not match the RPM, the object may appear to spin, move faster, or appear to go backward, depending on the relationship between the two rates. For this reason, achieving a match between the stroboscope frequency and the object's RPM is crucial for creating the illusion of a stationary object.