Stroboscopes (strobes) are used to freeze the motion of fast objects - such as vibrating or rotating machinery - as well as to measure their speed. They work by flashing light at different speeds.
In this simulation, the object repeats it's movement every 1 second (period is 1 second). The Observer can see the object's image (the strobe image) only when the strobe light flashes.
Adjust the Strobe's flash interval (period), until the strobe image appears to be sationary.
Is there more than one strobe flash period where the strobe image appears stationary? How would you decide which is the correct period, corresponding to the period of the object?.
What happens when the strobe period is
(An object's period is how long it takes to repeat. A bus that comes every 15 minutes has a period of 15 minutes. It's frequency would be once every 15 minutes (1/15 minutes) or four times per hour, because frequency = 1 / period. A ruler that vibrates once in 0.1 seconds has a period of 0.1 seconds, and a frequency of 1 / 0.1 = 10 vibrations per second)
Stroboscope effects can be seen in daily life, even without flashing lights. Spinning wheels, helicopter blades, can appear to spin backwards because of stroboscope effects caused by the sampling frequency of our eyes. Strange as it may seem, our eyes scan at about 10 hertz. Televisions display 25 to 30 frames every second, which is faster than our eyes' scan rate. This is why television images look as if they move smoothly, even though they don't.