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“The resistance and length of a wire are directly proportional. The longer the wire the greater the resistance. If you double the length of the wire then you double the resistance across it. This is because s the wire becomes longer, the ‘electrical slope’ (potential difference) across a given length becomes less steep. As the potential difference becomes smaller, so does the current, as the changes have less of a ‘potential gradient’ to ‘push’ them along in the wire.
A smaller current flows, therefore the resistance must be higher. ” (www.cyberphysics. pwp. blueyonder. co. uk/topics/physics/electric/resistance/LENGTH/Physics. htm) This is all beacause of what happens inside of the wire, the atoms in the wire and how the negativly charged electrons are colliding with the atoms and are then being caused to vibrate and therefore slow down. this then takes longer for the electrons to go through the circuit therfore causing resistance and making the rate of resistance higher as the lenght of the wire is increased. “This happens because of the electrons that flow through the wire.
These electrons travel at a steady pace, when they come to a different piece of wire, they have to slow down in order to be able to pass. (This is why the current differs). While moving through the wire, the electrons need to squeeze together. This is because there is not enough room/space for them to pass evenly through. The more the electrons have to bump together then the higher the resistance. This is because it will take longer for them to pass from one side of the wire to the other side. This is because the current is slowed down.
(The longer the wire, the longer the electrons have to stay squashed together, and so the longer they take to pass through the wire and the higher the resistance. ” – http://www. sci-journal. org/reports/vol3no1/v3n1k44. html Evaluation: Despite the problems that occured during this experiment I think that overall it was quite succesfull. There were some factors that could not of not prevented in the classroom, like that of the temperature but that had to be overlooked. My teacher said ” The temperature may affect the resistance in your circuit and may threrfore affect you results slightly.
” Inside the wire the temperature increases as the resistance does because the current begins to use alot more energy to get around the circuit and go against the resistance. This uses more electrical energy and then from that creates more heat energy. I don’t think that my graph of results was directly proportional, this could of been due to the flucuations that occured during some of our readings from the inaccuracy of the voltmeter and ammeter or just some of the leads or the wire not being secure enough. Although none of our results relly stande out as being “wrong” or not in line with the pattern of the rest of the results.
If I could redesign or of improved this experiment I would pay more attention to the fact that temperature is another factor which affects resistance within the circuit. I would try to counteract that by maybe leaving the wire to cool down between each reading, but making sure it for the same amount of time each time so to keep it a fair test. I would also use more accurate equipment such as a power pack to keep the voltage the same throughout to make the readings more reliable. I would also use a piece of wire that has the same cross-section throughout as that also affects the rate of resistance.
I would then use a more accurate device to measure the wire and a more stable way to keep it all in place, as sometimes the crocodile clips kept comming out of place or someone might of accidently of knocked them without realising. I would also use a more accurate ammeter and voltmeter as some of my results flactuated from time to time so I would use ones which go further than to just two decimal places. Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.