Objective: to investigate how the rate of resistance is affected by the different thicknesses (gauges) and the lengths of the wires.

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Amir Hussain 11 W

Science Coursework: Resistance Of Wire

Objective: to investigate how the rate of resistance is affected by the different thicknesses (gauges) and the lengths of the wires.

Theory Of Resistance Of Wire

What is V/I=R? V/I=R is the scientific theory behind resistance. This formulae can be also used as V=I*R meaning the same thing. What do they mean? V/I=R meaning voltage (V) + current (I) = resistance. Both current and voltage are measured similarly to each other by two dissimilar electrical measuring equipment. Voltage is measured by a voltmeter while current is measured by an ammeter. Current is the motion of electrons in a circuit. While voltage is the potential difference in a circuit. The circuit is simple to set up. But to make the circuit work you have to place the components in the correct positions or the current or electricity will not flow continuously. The voltmeter will be placed in the circuit opposite the component in parallel and the ammeter will be placed in series in the circuit anywhere. Ohms Law is a mathematical equation that displays the correspondence between Voltage, Current and Resistance in an circuit. The unit resistance is measured in, is Ohms (Ω) and is classified and understood like this; the resistance of a conductor is the ratio of the P.D. applied across it, to the current elapse through it. The theory of the Ohms Law states that as resistance increases, the harder it is for the electrons to pass through. The electrons cant pass through because there are frequent collisions. Materials that follow the Ohms Law are known as being Ohmic conductors. The thicker the conductor the lower resistance and the thinner the conductor the higher the resistance. The reason for this is because thicker conductors have a lower resistance as it is easier for electrons to pass through as the ions take up less space within the wire. There is a large amount of space for the electrons to pass through for this reason. In addition to this, the more space the electrons have to move freely, flowingly without any trouble the resistance increases. Furthermore if the resistance increases, so will the temperature of the wire. As the heat of the electrical conductor increases that means collision between atoms are increasing frequently. The change of heat occurs because metals contain large numbers of free electrons and as the electrons pass through the metal, they cross points and collide with the vibrating electrons. This is why heat and resistance have a positive relationship. As resistances increases, heat increases. The reason for the positive correlation is the ions starts vibrating more rapidly which makes it difficult for the electrons to pass through. The constant vibrating of the ions produces heat. Another theoretical theory states that to get low resistance the electrons have to travel a shorter distance. The cause for this is because there are fewer ions that the electrons have to avoid collisions with. When the collisions intensify this indicates that there is more resistance. Similarly that will mean more current and voltage. But there is something called a Superconductor which is totally different to this theory that resistance and heat increases with current. A Superconductor has no resistance at all and does not heat up because electrons are allowed to pass through the wires without transferring energy. For example mercury is a Superconductor. In order for mercury to become a superconductor it has to be cooled at 4.15K, -269oc.

Prediction

I predict from that, from gathering all my information from my scientific theory that, firstly as I increase the length of the wire, resistance will also increase. Also I predict that as I increase the thickness of the wire, the resistance will decrease at the same time. I say this because as I increase the length of the wire there will be extra nuclei’s on moving about for a lengthy time and distance. This occurs because the electrons have to travel a longer distance as the length of the wire has increased. This means that the probability of collisions between electrons and nuclei’s taking place is very likely as they have to travel a longer distance. On the other hand if the length is shortened, decreased the resistance will also decline. This is similar to why resistance increases, as the length of the wire increases. The main reason why the resistance will reduce is because there will be less nuclei’s and this means that the electrons will not collide with the nuclei’s frequently as there are not many, resulting to a decrease of the resistance of the wire.

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Four factors affecting the resistance in a circuit:

1. Length of Wire

 The longer the wire, the higher the resistance. The reason for this happening is because there will be greater amount of atoms in a lengthy piece of wire than a shorter one. This will mean that the collisions between the electrons and atoms will be more frequent as the possibility are high, very likely to happen. The consequence is the current will decrease and the resistance will increase.

2. Width of Wire

If a wire has a long width that will mean atoms will ...

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