Purpose: To verify Kirchoff's rules. To verify the rules for combining resistors which are in series and in parallel. In this experiment you will consider two circuits involving three resistors.

Discussion: The basic discussion in the preceding experiment applies to this experiment as well.

Procedure:
1. Make a two-loop circuit with a battery and three resistors as shown in Figure 1. Two of the resistors should be in series with each other. The third resistor should be in parallel with the equivalent resistance of the other two. Measure the voltage changes across the battery and each resistor. Check the loop rule for each loop.

2. There are two junctions in this circuit. Measure the current flowing through each resistor. Check the junction rule for each junction.

3. Use the measured voltage across each resistor and the measured current flowing through each resistor to calculate each resistance. They will not necessarily be exactly the same as the resistances marked on the resistors!

4. Use the voltage across points A and B (see Figure 1) and the total current in the circuit to calculate the equivalent resistance R_eq of the three resistors. Use the rules for combining resistors in series and parallel to calculate R_eq. How do the two values for R_eq compare?

5. Make a two-loop circuit with a battery and three resistors. Two of the resistors should be in parallel with each other. The third resistor should be in series with the equivalent resistance of the other two.  Measure the voltage changes across the battery and each resistor. Check the loop rule for each loop.

6. There are two junctions in this circuit. Measure the current flowing through each resistor. Check the junction rule for each junction.

7. Use the voltage across points A and B (see Figure 2) and the total current in the circuit to calculate the equivalent resistance R_eq of the three resistors. Use the rules for combining resistors in series and parallel to calculate R_eq (you may use the individual resistances calculated in step 3). How do the two values for R_eq compare?