Lab-In-A-Box

Lab-in-a-Box

Lab 1: Breadboard Basics and Ohm’s Law

Name: ______Pledge: ______(sign or type name)______

ID:______Date:______

Instructions: Answer questions 1 – 7 in Table 1, “No connections” should be indicated as “Overflow”. Show ALL WORK for calculations. Answers should be in BOLD and highlighted. Use Complete Sentences where appropriate.

Procedure

1.  Measure the resistance within one row. This is (typically) from points 1 to 2 in Figure 3 shown in Experiment 1 of the lab manual.

2.  Measure the resistance between vertically separated rows of power busses. This is (typically) from points 1 to 3 in Figure 3 shown in Experiment 1 of the lab manual.

3.  Measure the resistance between horizontally separated rows in the power busses. This is (typically) from points 2 to 4 in Figure 3 shown in Experiment 1 of the lab manual. How are the power busses in the ANDY board wired?

4.  Measure the resistance within one column of the device working area. This is (typically) from points 5 to 6 in Figure 3 shown in Experiment 1 of the lab manual.

5.  Measure the resistance between vertically separated columns in the working area. This is (typically) from points 6 to 7 in Figure 3 shown of Experiment 1 of the lab manual.

6.  Measure the resistance between horizontally separated columns in the working area. This is (typically) from points 5 to 8 in Figure 3 shown in Experiment 1 in the lab manual.

7.  Measure the resistance between rows and columns (i.e., between the power busses and the columns of the working area.) This is (typically) from points 1 to 5 in Figure 3 shown in Experiment 1 of the lab manual.

8.  What conclusions can you draw from this data?

______

Table I: Breadboard Measurements

Question / Resistance
1
2
3
4
5
6
7

Ohm’s Law

Figure 1: Circuit for verifying Ohm's law.

Analysis:

9.  Identify the unknown resistor shown in Figure 1 shown above. What value does the color scheme “Yellow Violet Brown” stand for?

10.  Calculate the current flowing through the unknown resistor and the voltage across it.

11.  Change the value of R1 = 5.6 kΩ and R2 = 3.9 kΩ, What is the color code for each resistor?

R1
R2

What is the total resistance of this circuit?

Using the voltage divider equation with the new resistors and calculate VAB.

12.  Using Ohm’s Law, if a requirements states to limit the current through the circuit to ≤ 0.4 mA. What total resistance would be required to achieve this current level? What standard resistor would satisfy this requirement as a replacement for R2 if R1 = 1kΩ?

Measurements:

13.  Construct the circuit shown in Figure 1 on your breadboard. Your circuit should be built to look like the picture. Trim your resistors to make the circuit look neat. Red wire for power, black wire for ground. Note that the 9V source is provided by the A/D board.

14.  Plug the black DMM probe into COM and the red probe into V on the DMM. Set the switch to the lowest volts scale that will not overflow for the expected voltage. 2V will only read up to 2V, etc.

15.  Measure the voltage across the R2 resistor. (See Section 2.5 for good technique.) Make sure your polarities are correct (i.e. Red Probe on Node A, Black probe on Node B. Be sure to include your units!

16.  Disconnect the wire from the unknown resistor to ground (wire BC).

17.  Move the red DMM probe from the “V” jack to the “mA” jack and set the DMM switch to the minimum full-scale value that will not overflow for the expected current calculated in step 10.

18.  Measure the current,, passing through the resistor by completing the circuit with the two DMM probes. To do this, place the red probe on node B and the black probe on node C. Review Section 2.5 for the proper technique for measuring current. Again, make sure your polarities are correct.

19.  Using Ohm’s law, calculate the resistance of R2.

20.  Remove the resistor from your circuit.

21.  Move the red DMM probe to the “R” jack and measure the resistance of the unknown resistor.

22.  What is the percent difference between your experimentally determined resistance in
step 21 and the measured resistance value found in step 23?

23.  What is the percent difference between the experimentally determined resistance found in step 21 and the nominal resistance value found in step 9?

24.  Change the resistance of R2 to be the standard resistor value found in step 12 that will have a current less than 0.4 mA. Measure VAB and IBC. Does the current meet the specification?

25.  Leave the first circuit on the breadboard. Build a second circuit similar to the first but now using the values in step 5. R1 = 5.6 kΩ and R2 = 3.9 kΩ.

26.  Measure VAB and IBC.

27.  Is the difference of the experimentally determined value in step 21 within 5% of the nominal value for the first circuit acceptable? Why or why not?

Last Revision: Rev 3.2: 08/29/2009

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