Electrical Resistance & Ohm's Law

PHY 201 & 231

Based on Loyd #28. Students measure the current in and the voltage across wire wound resistors for these objectives: Definition of the concept of electrical resistance of matter. Demonstration of the dependence of the resistance on the length, cross-sectional area, and resistivity of the wire. Demonstration of the equivalent resistance of resistors in series and in parallel arrangements.

Equipment

Notes

Set voltage to zero and current to 1 O'clock position. Current knob only sets maximum for safety, doesn't serve to vary output. As an option, the current ceiling may be set and knobs removed temporarily to prevent tampering. There are various versions/vintages of the apparatus. Check with instructor for preference. Put out two different DMM's at each table, for example, one Sperry and one Extech. If there are not enough Extech power supplies, use the Sargent-Welch power supplies.

This lab requires laptops. The computer cart containing the laptops can be wheeled by faculty into the lab room.