The efficiency of an eElectric motor Essay Example for Free

The efficiency of an eElectric labour sampleThe efficiency of the locomote in experiment 2 does decrease linearly with increasing mass as I predicted. Ideally the two graphs should follow each other since I employ the same motor in each experiment. However from my graph you stack see that my calculated efficiency for the second experiment is consistently about 9% higher than the calculated efficiency from my first experiment. This difference has probably been caused by the inaccuracy of the joule meter. This is inconsistent with my results from my calibration experiment. They channelizeed that the joule meter always records much verve that it is receives and therefore if I correct my results for experiment 2 it would make the motor even more efficient. However the linear sections of the graphs involve the same gradient and this targets that in both experiments the efficiency is varying in the same way. Extension choose To measuring the efficiency of the electric motor as a generator and to establish if the schema is quantify reversible. The experiment See Diagram for circuit digarm. Experimental method I will dropped a contour of loads a distance of 1.12m and then I recorded the amount of galvanising zipper produced by the motor using the joule meter Acknowledged Errors 1. The inaccuracy of the joule meter-however I can use my calibration slide to correct for this 2. Friction in the pulley system 3. The weight has kinetic energy when I hits the understanding and this energy is scattered from the system thus reducing the efficiency of the generator. My Results H=1. 12m load=10. 3 ohms grass (kg) Average Time for full drop(s) Joules recorded Exp1x10 Joules recorded Exp2x10 Average number of joules recordedx10 %E. efficacy Input (J) graphical record Explaining the graph The energy I put in the generator is profligate in three ways. 1. useful energy is dissipated in the load 2. Energy is lost in the rubbing of the pulley system 3. When current flows through the internal safeguard of the motor energy is lost 4. Energy is lost when the weight I drop hits the flawIt follows that because energy is conserved The Potential energy of the weight= Power dissipated in load + Work done against friction +Energy Lost in the motors resistance +Energy lost as the weight hits the floor M=mass, I=current, F=friction force, R=resistance, V=final speed of weight In my analysis I feel chosen to rebuff the energy lost in the internal resistance of the motor. This is sensible since the energy lost in the internal resistance was insignificant compared to the energy lost in the load. To further simplify things I will also ignore the energy lost as the weight hits the ground.This factor was very small because my weights travelled quite easy and they had small masses. Simplified formula for analysis Efficiency If you assume that the work done against friction is continuous this formula explains the 1-1/x form of my graph. For small we ights the generator is inefficient since most of the weights potential energy is organism used to overcome friction. For small the second term of the formula is large and the generator is therefore inefficient. This is shown by my graph. For large weights the work done against friction becomes insignificant and consequently the generator becomes more increasingly more efficient.For larger the second term would tend to zero and the efficiency should tend to 100%. My results do show that the efficiency increases for heavier weights however my results appear to approach an efficiency of 14% not 100%. This difference whitethorn be caused by the fact that for my larger weight the energy lost in the motors resistance and the energy lost as the weight hit the floor become significant. The inaccuracy of the joule meter may have also contributed to this difference. Is a the motor time reversible If my motor was time reversible it should behave in the same way irrespective of the direction of time.For example if you use electrical energy lift a weight with a motor if the system is time reversible you should be suitable to get the electrical energy back by dropping the weight. A motor is obviously time reversible to an achievement since it can be used both as a motor and a generator. However my results show that for my experiment you are lone(prenominal) able to retrieve a small fraction of the energy you used lifting when using the motor as a generator (about 2. 5 joules out of 150 or 2%). This inefficiency can be partially explained by considering the parts of the system that are not time reversible.This includes the friction in the system and the energy lost in the internal resistance of the motor. Here energy is lost as heat and sound that cannot be retrieved. Conclusion In general my experiments went well and I was able to use my result to make some useful conclusions. I was very pleased with the accuracy of my results. If I had more time I would have taken more experimental reading so that I could get a more complete picture of what was happening. I would also have spent more time calibrating the joule meter since its inaccuracy had a large effect on my results.Bibliography Sources used 1) Nuffield Advanced wisdom Physics student guide 2 unit H to L, Published by Longman, ISBN=0-582-35416-1 2) Web summon Motors URL=www. srl. gatech. edu/education/ME3110/design-reports/RSVP/DR4/Motors. http 3) Encyclopaedia Britannica CD-ROM 4) Encarta 99 CD-ROM by Microsoft 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.