Introduction For my coursework I am going to investigate “Ohms Law”. This states that the current flowing through a wire is proportional to the potential difference across it. I am going to test resistance through a wire from 0-80 centimetres at 10cm interval changing the voltage from 1. 5 to 3 to 4. 5 volts therefore repeating three times at each interval for reliability. Safety There are some rules and precautions to ensure safety while performing the experiment. We must: Tuck in our stools, tuck in our ties and stand during the experiment. Wear safety glasses. Not run.
Not mess about. Listen carefully to all instructions. Take our time. Not touch the nichrone wire. Hypothesis I think that the amount of current flowing through the wire will be directly proportional to the length of the wire. As the length increases so will the resistance proportionally. Apparatus I will need the following things for this experiment: A voltmeter, ammeter, battery power supply, key, stick with nichrone wire, metre stick and leads. Method Set up your apparatus according to diagram one after following the safety precautions. Place the key 10cm up the wire.
Record readings onto table from ammeter and voltmeteFind the resistances and average resistance and record these in a table. R1+R2+R3/3 = Average Resistance. Scientific Background Here I have a 5cm wire and a 10cm wire. Because there are double the amount of electrons in the 10cm wire than the 5cm wire there will be more collisions and therefore double the resistance. Interpreting and evaluating Upon reading my results I found out that my hypothesis was correct.
This was that the current flowing through the wire was directly proportional to the length of the wire. I know this because in the graph, the longer the wire, the higher the resistance. Fair Test In order to make this a fair test there are a number of factors that I must take the following factors into consideration: Make sure that the test is repeated the same amount of time for all lengths. Make sure that all of the voltages are the same for each length. Make sure that the key is held on the wire for the same length of time on all of the lengths. Results.
Here is a table of my results. Length Of Wire Current Resistance Voltage Av. ResistanceHere is a graph of my results. This graph shows a positive correlation between the two axis. Conclusion My conclusion is that the longer the wire is, then the higher the average resistance will be and we can see this in both the table and graph. Conclusion Ciari?? n McMullan 12c 1 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.