Strobobotac stroboscopes, MIT Strobe Lab. (Cambridge, MA), 1982-09-
Details >>

08 Stroboscopic

The strobe light’s ability to create optical illusions enables people to see images that occur too fast for the human eye to discern.

A stroboscope consists of three basic parts.  A power supply (an electrical outlet or battery) that sends electricity into a capacitor, which stores the electrical energy.  The capacitor dumps its stored-up energy into the third component, a tube filled with a rare gas, causing the gas molecules to vibrate rapidly enough to produce a bright flash of light.  The flash lasts until the energy is expended.  The fact that the flash is renewable makes the stroboscope so useful: as soon as the capacitor recharges, it is ready to go again.

You can see the strobe in action in Doc’s machine he termed the “piddler, ” in which two water streams flow downward and intersect above a catch basin. When a strobe light is used to illuminate the water streams, you can see the water stream as individual “droplets” of water. By adjusting the frequency of the strobe light, you can make the droplets appear to be stationary in midair. In addition, by further changing the frequency of the strobe light, you can make the stream of water droplets appear to flow upwards as well!

You can also see the strobe used on a fan:

hee-sc-09161
hee-nc-49001
hee-sc-01764
hee-sc-08023
hee-sc-08388
hee-sc-08804
hee-sc-08805
hee-sc-07732
hee-sc-07645
hee-sc-06774
hee-sc-07287
hee-sc-06299
Edgerton Lab Notebook 03, Page 105