I will use three different currents which will be 0. 2A, O. 3A and 0. 5A, then measure the voltage across the different lengths of wire they are 20cm, 40cm, 60cm, 80cm, and 100cm. This will be done for each current. We will have to vary the length of the wire so the results will be diverse and will also make it easier to produce a graph representing the results we will use three different current to obtain a reliable ohmic limit. I will then record my results in tables and produce of graph that will show me the ohmic limit. The power pack will be placed on 2V, so the current will be kept at a constant rate.

Method: Firstly I will collect up equipment and set it up as shown in the diagram. I will then set the voltage on the power pack to 3v, and place a 10cm length of nichrome wire between the two distances. Following this I will use the voltmeter to read the voltage across this length then use the ammeter to read the current flowing through this length to check if it is correct. I will then record my results on a table and repeat these steps for the rest of the lengths, increasing the length 20cm every time. Tables: Length (cm) Current (A) Voltage (V)Obtaining Evidence Length of wire (cm) Current (amps) Voltage (V) Resistance (?? Average Resistance ( Length of wire (cm) Current (amps) Voltage (V) Resistance (?? Average Resistance.

Length of wire (cm) Current (amps) Voltage (V) Resistance (?? Average Resistance Length of wire (cm) Current (amps) Voltage (V) Resistance (?? Average Resistance Length of wire (cm)Current (amps) Voltage (V) Resistance (?? Average Resistance (?? 6 Length of wire (cm) Current (amps) Voltage (V) Resistance (?? Average Resistance ( Length of wire (cm) Current (amps) Voltage (V) Resistance (?? Average Resistance Length of wire (cm).

Current (amps) Voltage (V) Resistance (?? Average Resistance Length of wire (cm) Current (amps) Voltage (V) Resistance (?? Average Resistance (Analysis Using the data I obtained from my experiment I was able to calculate the average resistance for each length, and then plot these averages on a line graph. From analysing my graph, I can see that there is a pattern.

Some of the results I recorded from my experiment correspond with my one of my hypothesis, in the beginning of my coursework, which states that the resistance of the wire will increase as the length of the wire increases. But on the other hand it goes against my second hypothesis which states that doubling the length of the wire will double the resistance, this relates back to Ohm’s law, which says that in electricity, the fact that the amount of steady current through a large number of materials is directly proportional to the voltage across the materials and inversely proportional to the resistance to the current.

My graph shows characteristics of being a non-ohmic conductor. I have stated this because, instead of the current being directly proportional to the voltage, which shows that it is a positive correlation, my graph on the other hand begins to level off in the last few lengths of the wire. The points on the graph begin to curve in such a way that increasing voltage produces a smaller increase in the resistance in the current. The points I have circled, are where the it should be increasing but instead begin to level off. This is why they show common characteristics of a non-ohmic resistor, because they to not obey Ohm’s law.

So an error has occurred whilst carrying out my investigations. Resistance of a wire Theory: What is resistance? Electricity is conducted through a conductor, in this case wire, by means of free electrons. The number of free electrons depends on the material and more free, electrons means a better conductor, i. e. it has less resistance. For example, gold has more free electrons than iron and, as a result, it is a better conductor. The free electrons are given energy and as a result move and collide with neighbouring free electrons. This happens across the length of the wire and thus electricity is conducted.

Resistance is the result of energy loss as heat. It involves collisions between the free electrons and the fixed particles of the metal, other free electrons and impurities. These collisions convert some of the energy that the free electrons are carrying into heat. The thin wire in a lamp tends to resist the movement of electrons in it. We say that the wire has a certain resistance to the current. The greater the resistance the more voltage is needed to push a current through wire. The resistance of a wire is calculated by Resistance (? )= Voltage (V) Current (I) Ohm’s Law.

It is also relevant to know of Ohm’s Law, which states that the current through a metallic conductor (e. g. wire) at a constant temperature is proportional to the potential difference (voltage). Therefore V i?? I is constant. This means that the resistance of a metallic conductor is constant providing that the temperature also remains constant. Furthermore, the resistance of a metal increases as its temperature increases. This is because at higher temperatures, the particles of the conductor are moving around more quickly, thus increasing the likelihood of collisions with the free electrons.