2050 words - 8 pages

Physics Coursework- Ohm's LawAim: To investigate the factors of affecting the resistance of a wire.In this experiment I will be using a metal nichrome wire to show the resistance when the length and width is changed.VariablesVariables that I am going to keep the same. Variables that I am going to change.Width- 0.36mm2Material- Nichrome wireVoltage- 2VTemperature- Room TemperatureLength- 10cm, 20 cm, 30cm, 40cm, 50cmMaterial- NichromeLength- 50cmVoltage- 2VTemperature- Room TemperatureWidth- 0.36mm2, 0.32mm2, 0.24mm2, 0.16mm2, 0.12mm2, 0.08mm2In this experiment I am going to use the nichrome wire as a conductor and I will be measuring the resistance by using an ammeter and a voltmeter because electricity can pass through the nichrome wire and the voltmeter will give me the volts produced and the ammeter will give me the amps produce, therefore these readings can be used to find the resistance.The resistance of a conductor is defined by the equation: R=VIResistance = Potential difference (Voltage)(V)Current (amps)Therefore I will be using this formula to give me the resistance, where the voltage divided by the current will equal the resistance.Metals conduct electricity because the atoms in them do not hold on to their electrons very well, and so creating free electrons, carrying a negative charge to jump along the line of atoms in a wire. Resistance is caused when these electrons flowing towards the positive terminal have to 'jumps' atoms. So if we double the length of a wire, the number of atoms in the wire doubles, so the number of jumps double, so twice the amount of energy is required: There are twice as many jumps if the wire is twice as long. The thinner the wire is the less channels of electrons in the wire for current to flow, so the energy is not spread out as much, so the resistance will be higher: We see that if the area of the wire doubles, so does the number of possible routes for the current to flow down, therefore the energy is twice as spread out, so resistance might halve.Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire.The factors of resistance are;1.Temperature: If the wire is heated up the atoms in the wire will start to vibrate because of their increase in energy. This causes more collisions between the electrons and the atoms, as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance.2.Material: The type of material will affect the amount of free electrons that are able to flow through the wire. The number of electrons depends on the amount of electrons in the outer energy shell of the atoms, so if there are more or larger atoms then there must be more electrons available. If the material has a high number of atoms there will be high number of electrons...

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