Resistance is a substance of resisting the flow of an electrical current. The quantity of resistance in an electric circuit. It controls the amount of current flowing in the circuit. The unit of resistance is the ohm. The standard abbreviation for electric resistance is R . The electrical calculation which is used to find out resistance The resistance of an object is determined by the length and the circular area of the object (width ), and by the temperature and material. The resistance is proportional to the object’s length, and inversely proportional to its circular area of the object (width ).

A material’s resistance increases with increases in temperature. Ohms Law Resistance is measured in Ohms with a symbol. -Ohm’s Law states “The current through a metallic conductor at constant temperature is proportional to the potential difference thus the potential difference / current is constant”. Predictions For Hypothesis 1 The resistance will nearly be directly proportional to the length of the wire. The longer the wire will be the higher the resistance will be. This is because there are more electrons, as there is more room for them.

This will mean there will be more collisions. This is a long piece of wire , it is more difficult for the electrons to get through because of the number of atoms blocking there root For hypothesis 2 The narrower the wire gets the higher resistance. This is because the narrower the This is a thicker piece of wire so more electrons can get through easily This is a thinner piece of wire and there is less room for the electrons to get through Variables For this experiment I can change the: 1. Different Metals of wire 2. Width of the wire 3. Length of the wire.

I have chosen to change the length of wire and keep the width at 0. 37 mm and I will be using nichrome for one experiment and for the other I have chosen to change the width and keep the length at 10 cm and will be using the same metal nichrome Once the results are found this is the formula, which is used: V R=__ I When R= resistance measured in Ohm’s I= Current in amps V= potential difference in volts Method To measure the resistance we set up the equipment as shown in diagram The different lengths of wire are measured out with fixed diameter and the same metal.

The two crocodile clips where attached to the two ends of wires. The wires are connected to the crocodile clicks. Then the wires are connected to the Meter. The reading is read off the meter and written down. This repeats for all the different lengths. Results Length of Wire Resistance 1st Reading 2nd Reading Average 100cm 7 The graph is on the next page showing the results Improvements These are improvement I would have made if I was to redo the experiment again I would make the wire taught so I get the exact length. I could have selotaped it to a ruler so it was exactly straight. Like the diagram below  I would not use crocodile clips because of their high resistance.

I would make sure the room temperature was always constant because the temperature affects the speed in which the atoms  I would made sure the two wires did not touch.  I would use other materials rather than just nichrome Further experimental work I would change the temperature of the experiment and see how this would affect the resistance. I would predict that it would raise the resistance as the atoms are vibrating faster so the electrons will not get through very easily. This is the equipment I would set up to show this theory: I could also change the way in which I measured the resistance.

I could use a voltmeter and an ammeter. I would put the voltmeter in parallel with the piece of wire and I would put the ammeter in series with the rest of the circuit. Conclusions My predictions where right as the resistance was nearly be directly proportional to the length of the wire. So the longer the wire will be the higher the resistance will be. 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.