In this investigation I will be looking at how the resistance of the wire changes when I change a factor and keep the rest constant.

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I will be changing the length of the wire and then investigation the change in resistance.


In this investigation I will be looking at how the resistance of the wire changes when I change a factor and keep the rest constant.


Background Knowledge

Resistance, in electricity, property of any object or substance to resist or oppose the flow of an electrical current. The quantity of resistance in an electric circuit determines the amount of current flowing in the circuit for any given voltage applied to the circuit, according to Ohm's law. The unit of resistance is the ohm, the amount of resistance that limits the passage of current to one ampere when a voltage of one volt is applied to it. The standard abbreviation for electric resistance is R and the symbol for ohms in electric circuits is the Greek letter omega, ?. For certain electrical calculations it is convenient to employ the reciprocal of resistance, 1/R, which is termed conductance, G. The unit of conductance is the mho, or ohm spelled backward, and the symbol is an inverted omega, ?.

The resistance of an object is determined by the nature of the substance of which it is composed, know as the resistivity, the dimensions of the object, and the temperature. Resistivity is expressed in terms of the ohms resistance per cubic centimetre of the substance at 20ºC (68ºF).

The term resistance is also used when the flow of a fluid or heat is impeded. The forces of friction provide the resistance to the flow of a fluid in a pipe, and insulation provides thermal resistance that reduces the flow of heat from a higher to a lower temperature.


I gathered this information from Microsoft Encarta '95 and The Dorling Kindersley.


Before starting my investigation I have decided to choose a factor that will affect the resistance of a wire. To help me decide what factor to choose, I will first analyse all the possible factors.
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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.

Material Of Wire: The type of material that the wire is made of 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 ...

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