Esistance and conductive putty Essay Example for Free

Esistance and conductive put on EssayThe aim of this investigation is to find out the relationship between foe and conductive apply, and to key out how length of putty affects this relationship. The Experiment Conductive putty is speci eachy designed to be a music director this is achieved by adding carbon black. This can easily be used to prove the concept of resistivity because it is pliant and so the cross-sectional area, length and shape can easily be changed. This try out go forth examine the effects on resistance in a duty tour, as the length of putty settles. I bequeath be using 30cm of putty, and decreasing it by 5cm each time.First the electromotive force of the battery will be taken using a voltmeter, and this will be recorded at the start of the experiment. Then a circuit will be constructed containing the battery, the ammeter and putty. See diagram. For each different length of putty, a reading will be recorded from the ammeter and when the practical has been completed, I will work out the resistance using the mandate R=VI. From those results I will draw a graph and then evaluate and conclude my experiment. diagram Constants My constants include the weight of my putty I am dismissal to start each experiment with 50g of putty.I will also sustain the same thickness of putty passim my experiment, and the same battery will be used constantly. Variables Possible variable stars in this experiment are temperature, voltage, cross-sectional area, mass, surface area and length. My variable is going to be the length of my putty, which will decrease by 5cm each time. I am going to start each experiment, using 30cm of putty. Fair Test To ensure my results are as accurate as possible, I will make sure my experiment is a fair test. For this, there should only be one variable.Other procedures can ensure it is a fair test, such as accurately measuring rod the putty to make sure it is decreased by 5cm exactly every time. The same battery shou ld be used throughout the experiment and to guarantee no results are anomalous, the experiment will be conducted trey times and a mean average will be taken from each result. Prediction and guess I predict that the resistance will be directly proportional to the length of the conductor so that if the length is doubled, the resistance will double providing all other factors remain constant.My hypothesis for this is that conductors suffer dispirit resistance when they are shorter because the electrons crap a shorter distance to travel so more vitality is hold since there are fewer collisions, and the current is higher. In the longer lengths, as free electrons move from division to atom some energy given off to disturb. The longer a conductor is, the more energy is unconnected to heat. The additional energy loss subtracts from the energy being transferred through the conductor, resulting in a decrease in current flow and an increase in resistance SafetyThe conductive putty is a harmless, non toxic and non-staining, however if gloves are not worn, your hands become black and you will need to moisten them. A lab coat should be worn to minimize marks on clothes and the experiment is conducted on a tray to reduce the possibility of a messy workspace. Apparatus list 50g of conductive putty 2 coins Tray to work on Knife Ammeter Ruler Voltmeter Wires Crocodile clips Gloves Method Put on gloves and rolled putty into 30cm long piece on the tray, trying to keep the thickness consist ant. Used voltmeter recorded the voltage of the battery. Connected battery to ammeter, and connected ammeter and other terminal of battery to putty by putting crocodile clips on the ends of the wires, clipping them to coins and placing coins at either end of the putty, this was done to make a reliable connection. See circuit diagram. Recorded reading from ammeter. Measured 5cm of putty with ruler and cut with knife. Re-attached putty to circuit. Repeated process, dedu cting 5cm from puttys length each time, recording the reading from the ammeter. Repeated experiment three times, which will enable me to spot anomalous results.Results I pay off calculated the resistance using the formula R=V/I. Resistance is measured in ohms and the unit uses the symbol ?. Experiment 1 battery voltage = 6. 12V Length of putty in cm Amps in A Resistance in ? Analysis of ResultsThis graph founds me the results for all three of my experiments, and there is a line of best fit for each experiment. There are some inaccuracies as the voltage was passably different for each experiment, and I feel that points for the later experiments are also out. This is visible in my results and is by chance due to the fact that the same piece of putty was used for all three experiments, and so heat from my hands must have affected results. I have taken the averages of my results.Length of putty in cm Resistance in ? These are my average results. These results were plotted on a gra ph (see graph) and they show a visible decrease in resistance as the length of putty decreases. This would prove my expectation and hypothesis to be correct, as it states that the putty will have lower resistance when the length is shorter or else than longer or the resistance of a conductor is directly proportional to its length due to factors such as loss of energy to heat, higher rate of collisions etc.(see prediction and hypothesis)However, when looking at my graph I noticed that the two points representing the shortest lengths of putty were out. This could be because as the putty was being worked, rolled and cut throughout the experiment it had become warmer and softer due to the heat from our hands this could have affected the resistance. Evaluation My results have proven my prediction and hypothesis to be correct, in that resistance is directly proportional to the length of the conductor, in this case the conductive putty.I think my results were quite accurate, but what may have let them push down was the fact that the batterys voltage was slightly different for each experiment and the coins used to connect the wire to the putty, did not stay in place very well. I also noticed there was often a big jump in amps and resistance between 10cm and 5cm of putty. This can be seen by looking at my results and the graph, and I have concluded that this is probably caused by my hands transferring heat to the putty by way of conduction, as the putty is regularly in contact with my hands during the experiments.I expect this could be dissociate experiment, in which we could investigate how temperature affects resistance. If this experiment was going to be redone, then I think I big businessman use a new battery for each experiment, and record the voltage as constant for all experiments. Also I would peradventure use a different method to connect the wires to the putty, like maybe sticking the wires directly and vertically into the ends of the putty.Another thi ng to do would be to use temperature or flush cross-sectional area as a variable alongside length, and to do a series of experiments involving change magnitude the length while decreasing the cross-sectional area, and vice versa. Conclusion I think this experiment was a success in that it proved the theory that resistance is lower with shorter lengths of conductor and my hypothesis declares that as the electrons have a shorter distance to travel if the length is shorter, there are fewer collisions and less energy is lost to heat unlike in a longer length of conductor, so the putty will have lower resistance.Therefore my hypothesis was correct and I have successfully concluded my experiment proving that resistance is directly proportional to the length of conductor. Show preview only The above preview is unformatted text This schoolchild written piece of work is one of many that can be found in our GCSE electrical energy and Magnetism section.