# 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.

by rendolw (student)

Lab No. 4

Current

Proving Ohm’s Law

By: Rendol Williams

Mr. Smith

Irmo High School

4A Physics SL

Friday, January 27, 2012

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. The total resistance in a series circuit can be calculated by adding the individual resistances of the resistors in the circuit together. A parallel circuit is a circuit containing more than one e-path. The resistance in a parallel circuit is determined by the sum of the reciprocals in the total resistance. For this experiment we will manipulate the equation V=IR so that it is solving for resistance. Resistance is then determined by dividing the voltage by the current. In making this change an alternative method for solving is created as the slope now represents the resistance in the system. The success of this lab is determined ultimately through the percent error calculated. In the case of a major percent error being found the student shall know that a random error or systematic error has occurred.

1. ## 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.
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