The efficiency of an eElectric motor Essay Example for Free

The capacity of an eElectric force EssayThe efficiency of the motor in experiment 2 does decrease linearly with increasing mass as I predicted. Ideally the two graphs should follow each other since I utilise the same motor in each experiment. However from my graph you can see that my figure 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 instaled that the joule meter always records more energy 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 suck in the same gradient and this shows that in both experiments the efficiency is varying in the same way. Extension Aim To measuring the efficiency of the electric motor as a generator and to est ablish if the system is conviction reversible. The experiment See Diagram for circuit digarm. Experimental method I will dropped a variety of cargos a distance of 1.12m and then I put down the amount of galvanic energy produced by the motor using the joule meter Acknowledged Errors 1. The inaccuracy of the joule meter-however I can use my calibration toot to correct for this 2. Friction in the pulley system 3. The heaviness has kinetic energy when I hits the ground and this energy is befuddled from the system thus cut back the efficiency of the generator. My Results H=1. 12m load=10. 3 ohms Mass (kg) Average Time for full drop(s) Joules recorded Exp1x10 Joules recorded Exp2x10 Average number of joules recordedx10 %E. might Input (J) represent Explaining the graph The energy I put in the generator is dissipated in three ways. 1. Useful energy is dissipated in the load 2. Energy is lost in the encounter of the pulley system 3. When current flows through the internal resistan ce 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 have chosen to treat the energy lost in the internal resistance of the motor. This is raw since the energy lost in the internal resistance was unnoticeable 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 slowly and they had small masses. Simplified formula for analysis susceptibility If you assume that the work done against friction is constant this formula explains the 1-1/x form of my graph. For small weights the generator is inefficient since most of the weights potential energy is creation used to overcome friction. For small the second term of the formula is gravid 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 may 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 deterrent example if you use electrical energy lift a weight with a motor if the system is time reversible you should be able to get the electrical energy back by dropping the weight. A motor is obviously time reversible to an extent since it can be used both as a motor and a generator. However my results show that for my experiment you are only 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 split 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 effectual 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 p icture 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 Science Physics student guide 2 unit H to L, Published by Longman, ISBN=0-582-35416-1 2) Web foliate 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 indite piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.