Ohm's Law Procedure

Introduction

Procedure

Configure your multimeter as an Ohmmeter. Carefully measure and record the resistances of each of your resistors. Record both the value indicated by the colored bands (nominal value) as well as your measured value. Always used the measured values in subsequent calculations - the nominal value is not accurate.
Connect the power supply and the resistors in series. Set the power supply voltage at 10V and set the current limit to 1.0 A. Refer to the Multimeter Lab or ask you instructor if you have forgotten how to do this.
Measure the current delivered by the power supply:
1. Create a gap in the wire that leads from either pole of your power supply to your circuit. Configure your multimeter as an ammeter, and use as a jumper wire to reconnect the gap. Keep red to positive. Do NOT probe in parallel across the power supply with your multimeter configured as an ammeter! You could damage the meter by doing this. Refer to the Mulimeter lab, or ask your instructor if you are unsure about how to measure current.
Using measured values of voltage and resistance, compute an equivalent resistance for the series combination and then compute a value for the power supply current. Compare to the measured value above using a percent difference.
Connect the power supply and the resistors in parallel. Again, measure the current delivered by the power supply. Compute the equivalent resistance and then compute the power supply current. Compare with a percent difference.
Verify Ohm's Law for each of the three resistors:
1. Configure your multimeter as an ammeter.
2. Connect the power supply to one of your resistors, leaving a gap in the connecting wire as in step 3.1.
3. Jump across the gap with your ammeter.
4. Set the power supply voltage. Use the voltage readout from the power supply as voltage data, and the ammeter reading as current data.
5. Record nine different values of voltage and current data on the Data page.
Plot Voltage vs. Current, and use the slope of this line to determine the resistance. Compare to the value measured with your Ohmmeter using a percent difference.
Repeat 6. and 7. for the other two resistors.

Percent Difference = (|difference|)/average) x 100%