J3-04. Electric Field Lines - Soap Bubbles

Purpose

To show the shape of electric field lines for a large dipole by observing soap bubbles move along the lines.

Equipment

Wimshurst machine, large aluminum sphere, small insulating stand for person, two long wires, and soap bubble◙blowing apparatus.◙

Setup Time

5 minutes.

Images

Description

A Wimshurst machine produces a high potential difference, one side of which is connected to a conducting sphere and the other side connected to a person blowing bubbles, forming an electric dipole. The bubbles attain the charge of the person blowing them and follow electric lines of force to the sphere, which has the opposite charge. A few bubbles will actually touch the sphere, pick up the charge on the sphere and return to the bubble blower.

References

Andrew A. Ruether, Smart Bubbles, TPT 33, 279 (1995).