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We will trace out equipotential lines around variously shaped electrode pairs. The electrodes will be drawn using conducting ink on a slightly conducting type of paper. A power supply will maintain the electrodes at different electric potentials and a multimeter can then be used to find the potential difference between any two points on the paper. You should have two pieces of conducting paper: one with dipole electrodes and one with parallel plates. 

1. Start with the dipole electrodes. Place graph paper underneath the conducting paper and mount the stack on the corkboard provided. Use one piece of graph paper for each member of your group. 
2. Connect the power supply to the electrodes by using thumbtacks to press wires leading from the power supply to the conducting ink. Make sure that you maintain a good connection. Adjust the power supply so that it places a potential of 12 volts across the electrodes. 
3. Configure your multimeter as a voltmeter and use a range appropriate for 12 volts. To trace out equipotential lines, place the black probe on the negative electrode and search for points on the conducting paper which are at a potential of some given voltage relative to the negative electrode. Start by tracing out the six volt equipotential line; locate at least 10 points at a potential of six volts and mark them by pushing a pin through the stack of paper. Locate other equipotential lines at 2, 4, 8 and 10 volts. Record the voltage of each line on the conducting paper for later use. Use pins to trace out the shape of the electrodes on the sheets of graph paper below.
4. Remove the graph paper and carefully trace out the electrodes and the equipotential lines. From these lines, trace out the electric field lines. The polarity of each electrode should be indicated and each equipotential line should be labeled with its corresponding voltage. Your electric field lines should be labeled with arrows to indicate the directions of the electric field vectors. 
5. Repeat 1 - 4 for the remaining electrode pairs. 
6. (For the parallel plate electrodes only) Make a plot of the voltage vs the distance x between each equipotential line and the negative electrode. Draw the best straight line through the data points and compare (using a percent difference) the slope of this line to a value of the electric field calculated using measured values of the power supply voltage and the plate separation.