Department of Physics and Astronomy

A linear pump produces a column of large, well-defined water drops that appear to be a continuous stream of water under normal lighting. Illumination of the column with a strobe light set at the frequency of the pump (60 Hz) creates the illusion of a series of stationary drops suspended in midair, as seen in the picture. Increasing the strobe frequency slightly makes the drops appear to move upward from the collector to the nozzle. For strobe frequencies slightly slower than 60 Hz, the drops appear to drift slowly downward. It is fascinating to watch the drops disperse through the reservoir mesh.

1. Be sure that the hose is not crimped.

2. Use a Variac to regulate water flow. Be careful to keep the electrical components clear of standing water.

3. Preset the strobe to 60 Hz before turning it on. Strobe frequencies of around 10 Hz can reportedly induce seizures.