Basic Idea:

• Measure the electric potential difference around two charges, and infer the direction of the electric field.

	What:	How Many:	Where:
	Conducting paper mounted on foam board	1	Majors storeroom, shelf E1
	Double-pencil probe	1	Majors storeroom, shelf E1 In the box with the conducting paper
	Digital multimeter	1	Majors storeroom, locked in steel cabinet
	9-volt DC battery	1	non-Majors storeroom, shelf L3
	Wires, 24" long	2 1 red, 1 black	Look around
	Widow maker	1	non-Majors storeroom, shelf L3
	Centimeter-ruled graph paper	1 sheet per person	Physics office
The following component is shared:
	40v regulated power supply	2	Majors storeroom, shelf C2
	Digital Multimeter	1	Majors storeroom, locked in steel cabinet
	Wires	3 – 12" 4 – 24"	104, 152 lab

Computers Needed?

• No.

• Lab Setup (see this page for detailed photos):

  

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• Pencil Probe:

  

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• Conducting paper connection — Connect conducting boards as shown. The wire that leads to the left-hand screw is marked with a piece of tape; make sure this screw is connected to the positive terminal. All boards should be connected so that the left hand screw has the positive voltage (when the student is facing the front of the lab).

• Power supply connection:
  • Note: Main DC power panel must be disconnected before the 40v power supplies is used! Jeff will take care of this.
• Two 40v DC power supplies are connected in series; both are set to 15.0 volts.