In the lab, equipotential lines can be found experimentally by using a voltmeter and finding points
around a certain charge distribution that are at the same voltage (electric potential). When these
points are determined and marked, they may be connected to form the equipotential lines. Field
lines can then be drawn perpendicular to the equipotential lines.
The types of charge distribution that will be used in this experiment are:
Fig 4 Equal and opposite point charges (an electric dipole)
Procedure:
1) Use silver pen to make electric dipole (two silver dots) types of charge distributions on the
conducting paper.
2) Fix the conducting paper on the corkboard with a several sheets of regular size white paper
underneath so each member of the group can have one paper.
3) Press two metallic tacks into the center of the silver spots and into the corkboard.
4) Connect the dc power supply to the tacks with appropriate wires.
5) Set the power supply to an appropriate voltage so that the voltmeter shows enough
sensitivity on the conducting paper.
6) Place one terminal of the voltmeter at point A and with its other terminal search for points
on the conducting paper that are equipotential with point A. At any of these points, the
voltmeter should read zero. Locate a set of points that are about or at most 1 inch
apart. Make a hole where each point is found by pressing a tack through the paper(s) into
the corkboard.
7) Repeat steps 5 and 6 for each of points B, C, D, and E. For any of these points you will
find a curved equipotential line.
8) Turn off the power, disconnect the voltmeter, and remove the tacks placed at the silver
spots. Each student must obtain one sheet of white paper placed underneath the conducting
paper with holes in it.