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Series-Parallel Circuits Lab


1. Calculate and measure the voltage, current and resistance characteristics of complex series parallel circuits.

Materials and Equipment:
1. DC Power Supply
2. 2 DMMs (one for measuring voltage, one for current)
3. Protoboard (breadboard)
4. Various Standard Resistors


1. Given Figures 1 to 4, draw a pictorial diagram of the circuit as it will appear on your protoboard (see lab notes). Before doing so, note the orientation and layout of the board.

2. Calculate and measure all values for the circuit in Figure 1 and indicate them in
Table 1.

3. Calculate and measure all values for the circuit in Figure 2 and indicate them in Table 1.

4. Calculate and measure all values for the circuit in Figure 3 and indicate them in Table 1.

5. Calculate and measure all values for the circuit in Figure 4 and indicate them in Table 1.

Note: You may want to do the calculations for each circuit before coming to lab.

Questions and Analysis:

Your answers to the questions below should show some thought. There may not be a simple answer to each question. For questions 2 through 4, you may want to verify your answers by measuring the effect. Include your answers as part of your report.

1. In general, compare measured results with calculated results and suggest reasons for differences (greater than 5%)

In general, all of my results were pretty accurate. That is I did not have any that were greater then five percent off from the calculated answer. In fact the largest percent error I had was 3.38% off of the calculated answer.

2. What would happen if R7 were removed from circuit 3 in Figure 3?

If R7 were removed from the circuit the total resistance would lower while the total current and current flowing through all of the other resistors would increase.

3. What would be the effect in circuit 3 if R1 were open?

The effects on circuit three that R1 would have on it, would be that the circuit would become an open circuit and that current would no longer be able to flow through it.

4. If circuit 3 was on a PC board or soldered such that no connections could be removed, what tests would you make to determine if R1 were open as in part 3?

One of the tests that you could perform to test if R1 was open or not would be to hook up the circuit to a
DMM and measure the total resistance or even the resistance of R1 because if it was open then it would have an infinite resistance. However, you would not be able to hook up a DMM and try to test the current because since all of the ends are soldered down you would be able to check it because current must be checked in series with a circuit.


The main discovery I learned from this lab was the right and wrong way to measure current in a circuit. I first tried to measure the current across the circuit instead through it. Immediately I realized the error, and with some help I was able to figure out what was being done wrong. All my calculations and measured values were generally pretty accurate as noted in Tables 1 - 4. For example, the calculated value on circuit 1 for the value of R2 was 11.544V and the measured value was 11.55V, thus making the percent error 0.052%; found by using the equation (measured value - (calculated value / calculated value)) x 100.

Lab Notes
Lab Notes Page 1 of 5
Lab Notes Page 2 of 5
Lab Notes Page 3 of 5
Lab Notes Page 4 of 5
Lab Notes Page 5 of 5

Lab Data
Circuit 1 - Measured and Calculated Values
Circuit 2 - Measured and Calculated Values
Circuit 3 - Measured and Calculated Values
Circuit 4 - Measured and Calculated Values

Electrical Engineering lab key words: series parallel circuit, combination, series measurement, parallel measurement, current, voltage, breadboard, prototype circuit board, circuit layout, digital Multimeter, DMM, schematic, resistance, impedance, resistor, open circuit, short circuit, percent error, 1/4 watt, percent error calculation.

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