Simple DC Circuits

Materials needed for this activity:

0 - 15 V DC power supply;
breadboard (or connecting wires with alligator clips);
five resistors (three of which are different; all less than 100 ohms);
a multimeter or VOM (
click here for a primer on how to use a VOM) or
voltmeter sensitive to .1V to 15 V and an ammeter sensitive to 0 - 500 ma.

Procedure

1. Connect a resistor to the power supply. Verify that its advertised (use color code) resistance rating is accurate by measuring the resistance with the meters. Voltmeter in parallel, ammeter in series. Tag this resistor as R1.
2. Repeat step 1 for each of the other resistors.
3. Connect the five resistors in series to the power supply and measure the output voltage. (Note that this value will change from circuit because of something called internal rresistance.)

STOP!!!

4. Pretend that you have been given an in-class problem to solve. It has five resistors connected in series to a power supply. Calculate what should be the voltage and current for each resistor as though it were an in-class problem.

5. With these predictions in hand, use the appropriate meter to measure the voltage and current for each resistor.

6. Repeat steps 3 - 5 for other circuits using the five resistors.

7. For each circuit in number 6 above, you should have two tables to report: one table should have the predictions for the circuit; the other should have the measured value.