The purpose of this lab is to prove the discovery of George Ohm, that when the temperature of a metallic conductor is kept constant, the current through the conductor is proportional to the potential difference across it.

2. Procedure

1. Obtain the materials needed which were an energy source, ammeter, and multiple alligator clip wires, two 250 Ohm resistors, and a 100 Ohm resistor.
2. Construct a single resistor circuit connecting the energy source, ammeter and resistor using the alligator clip wires while the power is off.
3. Turn on the power and cue it to 1.5 V. Record the current value as shown from the display on the ammeter. Switch to 2.2 V and record current. Switch to 3.0 V and record current. Switch to 4.5 and record the current. Switch power off when done.
4. Next, construct a series circuit using all three resistors connecting the energy source, ammeter and resistor using the alligator clip wires while the power is off.
5. Turn on the power and cue it to 1.5 V. Record the current value as shown from the display on the ammeter. Switch to 2.2 V and record current. Switch to 3.0 V and record current. Switch to 4.5 and record the current. Switch power off when done.
6. Construct a parallel circuit connecting the energy source, ammeter and resistor while the power is off.
7. Turn on the power and cue it to 1.5 V. Record the current value as shown from the display on the ammeter. Switch to 2.2 V and record current. Switch to 3.0 V and record current. Switch to 4.5 and record the current. Switch power off when done.
8. Construct a complex circuit connecting the energy source, ammeter and resistor using the alligator clip wires while the power is off.
9. Turn on the power and cue it to 1.5 V. Record the current value as shown from the display on the ammeter. Switch to 2.2 V and record current. Switch to 3.0 V and record current. Switch to 4.5 and record the current. Switch power off when done.

2. DATA COLLECTION AND PROCESSING

1. Raw Data

2. Calculated Data

Average Voltage= 2.8 V

        Single                Average Current= .0104 ± .005 A

                        Thus using the equation R=      R= 269.2 Ω  

Average Voltage= 2.8 V

        Series                Average Current= .0045 ± .005 A

                        Thus using the equation R=      R= 622.2 Ω  

Average Voltage= 2.8 V

        Parallel                Average Current= .0463 ± .005 A

                        Thus using the equation R=      R= 60.5 Ω  

Average Voltage= 2.8 V

        Complex                Average Current= .0118 ± .005 A

                        Thus using the equation R=      R= 237.3 Ω  

                Percent Error

        Single                

                         = 7.7%

        Series                

                         = 3.7%

        Parallel                

                         = 10%

        Complex                

                         = 5.6%

Total Percent Error= 6.75%

                Graphs

Conclusion and Evaluation

1. Conclusion (ASPECT 1)

This lab experiment was a huge success! I believe this lab solidified the understanding of Ohm’s Law and the elements given forth in his equation V=IR. The elements of voltage, current and resistance all played an important role and showed how they can be used to find values and prove the validity of Ohm’s Law. The use of the equation also gave the student an increased awareness of the relationship of voltage and current to the relationship involving resistance.

2. Evaluation (ASPECT 2)

There were many clear errors that were found in this experiment. There was the random error of resistance being contained in the ammeter that was from old wires or some unknown force. This resultantly gave us skewed results on the actual amount of current running through the circuit. Another error was the systematic error of the reader reading the value of the current. The problem of parallax occurred as the perspective of different students led to different results and a larger uncertainty which leads to a decreased amount of accuracy. The final error we observed was that the alligator clips contained resistance within them and thus skewed the results.

3. Improvements (ASPECT 3)

We can fix these problems by simply making a few alterations to the experiment. In regard to the problem of parallax a digital form of an ammeter would surely eliminate this issue. We can fix the error of resistance in the alligator wires and the ammeter by finding a better form of conductor that offers a less noticeable form of resistance on the circuit system.