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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.

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Introduction

Lab No. 4

Current

Proving Ohm’s Law

By: Rendol Williams

Mr. Smith

Irmo High School

4A Physics SL

Friday, January 27, 2012

  1. DESIGN

  1. Introduction

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. This statement is known as Ohm’s Law. It is represented in the equation V=IR. By manipulating the elements of Ohm’s Law students will be able to test the validity of Ohm’s Law. The elements which include Voltage measured in volts, Current measured in amperes and Resistance measured in Ohms. Voltage in a circuit is the force that pushes the electrons along the path. Current this is the amount of charge per unit time that passes through the cross-sectional area of a conductor. Lastly resistance is the ratio of voltage across a conductor to the current through it. A series circuit is a circuit containing only one electron path or e-path for the electrons to move across.

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Middle

DATA COLLECTION AND PROCESSING
  1. Raw Data

Circuit Type

Voltage

(V)

Current

(mA)

Accepted Resistance (Ω)

Single

0 V

1.5 V

2.2 V

3.0 V

4.5 V

0 mA

5.5 ± .5 mA

8.2 ± .5 mA

11.3 ± .5 mA

16.7 ± .5 mA

250 Ω

Series

0 V

1.5 V

2.2 V

3.0 V

4.5 V

0 mA

2.5 ± .5 mA

3.5 ± .5 mA

5.0 ± .5 mA

7.0 ± .5 mA

600 Ω

Parallel

0 V

1.5 V

2.2 V

3.0 V

4.5 V

0 mA

25.0  ± 1 mA

37.0  ± 1 mA

50.0 ± 1 mA

73.5 ± 1 mA

55 Ω

Complex

0 V

1.5 V

2.2 V

3.0 V

4.5 V

0 mA

6.5 ± .5 mA

9.5 ± .5 mA

12.5 ± .5 mA

18.5 ± .5 mA

225 Ω

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Conclusion

  1. 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.

  1. 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.

...read more.

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