the resistance of a conductor is the opposition of the conductor to the current flowing through it

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Jonathan Shields IVCH   Resistance Coursework

Introductory theory

According to “Calculations for A-Level Physics” by T.L. Lowe and J.F. Rounce, the resistance of a conductor is the opposition of the conductor to the current flowing through it, and is defined as the potential difference needed across the conductor per ampere of current. Resistance is measured in ohms (Ω), from ohms law stating the equation: R=V÷I

Where R is resistance (Ω), I is current (amps), and V is voltage (volts). Resistance is virtually the negative electrons passing through the wire being attracted to the positive ions making up the metal that is the wire. Resistance is the heat given off when  negative electron and a positive ion come together, thus the more positive ions the more resistance.

So we could use the analogy of a corridor with people, who are the positive ions in the wire, trying so catch tennis balls, the volts passing through the wire. If you throw lost of balls, high voltage, they will catch a few of the balls, but a lot more balls will pass through, low resistance. If you lengthen the wire, think of it as adding more people, then more balls will be caught, thus increasing the resistance. If you shorten the wire there will be a less people to  catch the balls, allowing more current to pass through, thus decreasing the resistance.

Other factors that could be investigated: width of cross-section of wire.

                                     length of wire.

                                                            temperature.

                                type of wire.

        Widening the wire should increase the amount of space for the electrons to pass through, thus decreasing the resistance, this means that the positive ions making up the wire would be more spread out, therefore leaving more space. I think that doubling the size of the cross section should halve the resistance in the wire, since more space inside the wire for the current to avoid the positive ions if kept at the same temperature. The length of the wire should increase the resistance since there will be more of a chance it will hit a molecule in the wire, which are usually single atoms and these are held together by electrical forces. These forces involve the sharing of electrons and these electrons are free to move at random within the metal. 

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So we should think of a metal as consisting of ions rather than atoms.  Therefore the further the current has to travel, the resistance should increase, using this theory I can predict that doubling the wire should double the resistance, again, in a fair test where the temperature does not change.

Temperature will effect my results due to when metals are heated the expand(get bigger, since heating causes vibrations in the metal, this would cause the positive ions to move around in the wire, this would cause more resistance, and therefore decreasing the temperature less resistance.

The type of ...

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