Observing the display of a ‘floating image’ clock relies on the phenomenon of
‘persistence of vision’. The clock has a wand with a set of flashing light-emitting diodes
(LEDs) at its end. The wand oscillates rapidly back and forth and takes only 0.0625 s tosweep from one end to the other. The wand becomes almost invisible to the eye, while the flashing LEDs create a floating image effect.