# KIRCHHOFF'S RULES

## Gunn Physics

PURPOSE:

The purpose of this lab will be to gather experimental data for the circuit below to analyze in light of Kirchhoff's Rules for electrical circuits.

MATERIALS:

• Circuit Experiments Board
• Digital Multimeter (DMM)
• Resistors
• Battery
• Wires

PROCEDURE:

1. Measure and record the resistance of your five resistors, choosing which ones will be designated R1, R2, etc.
2. Connect the circuit shown below using your resistors. Use the diagram above as a reference as you record your data. With no current flowing (the battery disconnected), measure the total resistance of the circuit between points A and B.

3. With the circuit connected to the batteries and the current flowing, measure the voltage across each of the resistors and record the values in the Data Table. On the circuit diagram above, indicate which side of each of the resistors is positive relative to the other end by placing a "+" at that end.
4. Now measure the current through each of the resistors. Interrupt the circuit and place the DMM in series to obtain your reading. Make sure you record each of the individual currents, as well as the current flow into or out of the main part of the circuit, IT.

 RESISTANCE W VOLTAGE volts CURRENT ma R1 V1 I1 R2 V2 I2 R3 V3 I3 R4 V4 I4 R5 V5 I5 RT VT IT

ANALYSIS:

1. Determine the net current flow into or out of each of the four "nodes" in the circuit.
2. Determine the net voltage drop around at least three (3) of the six or so closed loops. Remember, if the potential goes from negative to positive, treat the voltage as positive (+), while if the potential goes from positive to negative, treat it as negative (-).

DISCUSSION:

• Use your experimental results to analyze the circuit you built in terms of Kirchhoff's Rules. Be specific and state the evidence for your conclusions.

EXTENSION:

• Build the circuit below and apply the same procedure you used previously. Analyze it in terms of Kirchhoff's Rules. If possible, try to analyze the circuit ahead of time and compare your measured values with the theoretically computed values.