The resistance of a wire varies with its length Essay Example for Free

The resistance of a wire varies with its length Essay To investigate how the resistance of a wire varies with its length Equipment Needed: o power pack o 5 wires o Voltmeter o Length of wire o Ruler o Ammeter o Crocodile clip Circuit Diagram: Prediction: The equation V=IxR is how you find the resistance rate. Im now going to re-arrange it to R= V for this to work the temperature has to stay I Constant or it will not work. So I predict that if I increased the length of the wire the resistance will be increased. So I think that if you double the length of the wire the resistance will be doubled. Method: o Collect the equipment and set up the circuit by measuring the wire o Turn on the power pack. o Slowly increase the power o Connect the crocodile clip onto the copper wire to make the circuit complete. o Using a ammeter to measure the amount of current in the circuit o Using a voltmeter to measure the amount of voltage across the circuit o Record results Repeat this with all the different lengths on the wire. Also on the experiment make sure that you read the meter from directly in front by using parallax. Another thing makes sure that the needle is not moving around this then makes the measurement correct. Fair Test: To make this a fair test Im going to keep everything the same in each test apart from the length of wire. The wire will be the same thickness and material every time. Safety: Its important that the wire does not get to hot that it burns. To prevent this from happening I wont let the current go any higher than 2amps. Preliminary work: Current (A) Measurement (CM) Voltage (V) 2. 0A 10CM 0. 4 1. 5A 10CM 0. 3 1A 10CM 0. 2 0. 5A 10CM 0. 1 Current (A) Measurement(CM) Voltage(V) 2. 0A 90CM Off scale 1. 5A 90CM 3. 4 1. 0A 90CM 2. 5 0. 5A 90CM 1. 0 We decided not to use a current of 2 Amps because it melts the wire. The other thing was we decided not use 90CM because one of the readings was off the scale. Practical Results: Length (CM). Current (A) Voltage (V) Corrected Resistance ( ) CorrectedLength (CM) Current (A) Voltage (V) Corrected Resistance ( ) Corrected Length (CM) Current (A) Voltage (V) Corrected Resistance ( ) Corrected   Our meter read 0. 1V even when no circuit was connected so I had to take this reading off all the results which is why there is a corrected column. Length (CM) Average resistance (ohms) Conclusion: I have noticed that as the length of the wire increases the resistance also increases. This happens because: This all happens because the resistance has doubled like I said in my prediction. I checked this by looking on my graph E. g. 20CM= 0. 44 40CM=0. 88 80CM=1. 76 See each time it has doubled. Evaluation: We found out that there was an error in our voltmeter which meant our first point was on 0. 1. This made our results incorrect which meant we had to re calculate the numbers. We read all our results to one decimal point instead of two. I have an Anomalous point at 20cm. I can see from my results there was a error at 15amps. If I ignore this result and take an average of 0. 5+1. 0amps I get a point that lies on my line. I have shown this on my graph in red. This error accrued by reading the metre wrong. Holly Atkins Page: 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.