This is because if the wire was twice as long it would have twice as many atoms for the electrons to collide with making it twice as hard for the current to flow. The rheostat is there to control the current and an ammeter to measure this control. Also, by using another wire, other than constantan, we could see how temperature affects resistance, although, one would need to have done a constantan experiment in order to understand the dynamics of the other factors, otherwise the experiment would be to complicated. The radius is half the diameter so it should therefore be 0. Keep the wire cool all the way through the experiments, as heat is also another variable in the resistance of the wire.
Most ceramics and plastics are poor conductors and are therefore called insulators. So, if you double the diameter, you will quarter the resistance. Wider wires have a greater cross-sectional area. I will make sure that I will not drop any dangerous equipment onto the floor, my hands and on other people also. The length of the wire will be changed by moving the crocodile clip across the wire on a ruler. As the length of the wire doubles, so does the voltage and so does the resistance. This is the variable which we will be changing in the experiment.
I found that the resistance increased as the thickness of the wire decreased, however, when I did the test with the copper wire I found that it was so unresistant that there would not be a lot of point in conducting my experiment using a copper wire because I would not really be able to compare the results. The Temperature when the wire gets warmer and warmer the metallic ions will vibrate more and more making it harder for the electrons to move, just like when you're in a room with dancing people. A 12-gauge wire is wider than 14-gauge wire and thus has less resistance. I shall then conclude my findings and present them with tables and graphs saying what we discovered. More collisions mean more resistance. This means that some materials will have varying resistances for the same voltage and current than others.
Wire 1 has length L and wire 2 has length 2L. Temperature: An increase in temperature will increase the resistance Cross Sectional Area: The larger the wire, the less resistance The length of the wire: The longer the wire, the more resistance The material of the wire: Some materials are better conductors than others, and this causes … less resistance Resistance is inversely proportional to cross-sectional area. The graph should show that my hypothesis is correct and that the resistance will increase as the length of the wire increases. In the circuit there will be a rheostat, voltmeter and an ammeter. Before I can carry out my real experiment, I will need to do a preliminary experiment that will tell me how much voltage I will need for the varying lengths of wire. The following is a list of variables that can be changed in the experiment that I will be doing: ÃÂ·Changing the length of the wire ÃÂ·Increasing the cross-section of the wire ÃÂ·Changing the material used ÃÂ·Changing the temperature ÃÂ·Changing the resistance of the wire ÃÂ·Changing the voltage going across the wire ÃÂ·Changing the current going across the wire For my experiment I will proceed to test out whether the length of the wire will affect the average resistance.
This would have prevented the area of the wire from remaining constant and would have affected my results. The resulting increase in the average vibration kinetic energy is rise in temperature. Analysis of Results: From the graph and table of results i can see a pattern emerging. This is why I kept a constant current at 0. I will alter the lengths of the wire by attaching the copper wire to a metre ruler stick and adjust the other wires so that they are attached at the different lengths specified. Conductors have a low resistance. The type of Metal the type of metal.
From this graph, we can immediately see a few things. Going beyond that voltage results in current flow short and a significant reduction in resistance. Most resistors have stripes or bands of colors painted on them. Two wires - A and B - with circular cross-sections have identical lengths and are made of the same material. If there is two wires of equal dimensions, and if one wire is made of pure … golf while the other is made of lead, then the wire of Gold will have less resistance.
Procedure a Connect up a series circuit of two cells, and the ammeter, with a 30 cm length of one of the wires closing a gap between two crocodile clips. Answer - None of the above. Conductors: Materials that allow electric current to flow through them easily are known as conductors. The more difficult The equation implies that the resistance is inversely proportional to cross-section, so doubling the cross section should halve the resistance. Some cell holders have clips which can bridge the insulator causing a 'short circuit'. As this is the correct value, I can work backwards to see that the previous calculations were correct.
A smaller potential gradient less volts per metre means current decreases with increased length and resistance increases. As you heat a conductor such as a copper wire the extra heat energy causes the atoms in the wire to vibrate more rapidly the flow of electrons which is what electricity is are impeded by the more rapidly vibrating atoms getting in the way of the electrons so the resistance of a conductor rises with temperature. The cross sectional area is inversely proportional to the resistance of the wire. This experiment has two sections which have to be carried out in order to get the correct results: Preliminary work: Find out which wire is the best insulator? Wire 1 has radius R, and wire 2 has radius 2R. The thinner the wire, the less power amperes it can pass. We can also measure the gradient of the graph. A 20-Amp circuit used for wall receptacles should be wired using 12-gauge wire and a 15-Amp circuit used for lighting and fan circuits should be wired using 14-gauge wire.
The potential difference is often just referred to as the voltage. No Insulator is 100% as a tiny almost immeasurable amount of power still finds it way via impurities or its' general natural conductivity. The standard metric unit for resistance is the ohm, represented by the Greek letter omega -. Consistent with the discussion above, this equation shows that the resistance of a wire is directly proportional to the length of the wire and inversely proportional to the cross-sectional area of the wire. Take an average of the 3 tests to ensure accuracy 8. An increase in cross sectional area results in a decrease in resistance. These electrons travel around the circuit at an even pace.
Use the widget below to determine the resistance value from the colored stripes. Perhaps you're doing a lab and need to know the resistance of a resistor used in the lab. This means I can find and record the resistance. I could also consider using different cross-sectional areas of wires or even change the temperature of the wires deliberately and see how manipulating these variables affect the resistance of the wire. But note: if the current is too large, the voltage of the cells will fall due to their internal resistance. White and gray White and gray indicate a neutral wire.