Looking every so often
Physics Narrative for 11-14
How a stroboscope works to allow study of high-frequency vibrations
A big problem in trying to figure out what's going on as we hear sounds is that the vibrations tend to be too fast to see directly. One way to make the effects visible is to use a stroboscopic device.
A stroboscope allows you to see the vibration through a series of snapshots, spaced so that you catch the vibration a little later on in its cycle each time.
This gives a slow motion view of what is happening – slow enough for the eye to see. You can strobe either by flashing a light, thereby illuminating the scene for very short bursts, or by putting a rapidly opening and closing shutter in front of the detector – often the eye. You can even strobe just by waving the outstretched fingers of your own hand in front of your eye. All you need to
strobe is to take regular snapshots of a scene, looking only at regular intervals.