In this experiment I will be investigating the efficiency of a motor. I hope to calculate a range of results when the motor lifts varying weights Essays

In this experiment I will be investigating the efficiency of a motor. I hope to calculate a range of results when the motor lifts varying weights Essays In this experiment I will be investigating the efficiency of a motor. I hope to calculate a range of results when the motor lifts varying weights Essay In this experiment I will be investigating the efficiency of a motor. I hope to calculate a range of results when the motor lifts varying weights Essay Safety: In this experiment it is important to consider the safety aspects when carrying out this practical task; I will make sure of the following things before starting the experiment: * The circuit has been connected correctly according to the circuit diagram (Previous page) * Make sure that the connected leads are all working in order and are not tangled * Check that the motor is working correctly * The Power supply is working, and the voltage is not exceeding the limit * Check the circuit before starting and be standing during the experiment * A Mat should be placed on the floor as weights will land on to the ground Keeping the same Changing Current Length of string /Height Temperature Voltage Motor Weight Variables: Theory: Efficiency is often expressed as a percentage. What efficiency shows us is the power wasted in the experiment, not all the power is used efficiently as it is wasted when the power is being transferred. The power source is transferred usefully in the external load, while wasted power is used heating the power supply and surroundings. No motor can work perfectly, due to friction and other small factors. In other words, some energy is always lost and you never get out the energy you put in, this is what is being tested in this experiment therefore we hope to see if the energy is transferred well or not. the equation for efficiency is known as: Efficiency = useful energy (power) output/ total energy (power) input x 100 The main factor that stops efficiency from reaching a maximum is friction as it can not be eliminated it therefore brings the total efficiency down. Resistance can play a big factor in affecting the experiment the more resistance in the circuit the less efficiency. The resistance will slow down the motor. The higher the temperature the more resistance that will be produced as the temperature increase the electrons will vibrate more causing more friction in the motor and making it less efficient. The resistance will stop the current flowing as well and could lead into anomalous results. In this experiment I will be using the following to calculate the efficiency of the motor: WH/ IVT This will show the efficiency of a motor and will allow me present my results using the equation. The equation basically shows work done (WH) and the power input (IVT). Prediction: In this experiment as we increase the weight the motor will have to do more work it will then also take longer for the weights to be lifted, and as it does more work its efficiency will increase as the current and voltage will remain the same. So if you double the weight, the work will double and so should the efficiency because the motor becomes more efficient as it does more work for the power being supplied. If the length of the string is longer the results will be more accurate as it will take longer for the weights to be lifted to the top of the work top. Therefore if the length was increased the results could be more accurate and it would make the overall work of the motor increase. If the voltage was changed with the weights the efficiency would remain the same as the work would be done easier if there was more overall power input. Therefore if the voltage was doubled and the weight was the doubled the efficiency would remain constant. Method: In this practical I am going to change the weight and voltage, as two separate studys. I will do this by planning out how I will conduct the experiment: * Cut string at 1 metres length * I will tie the wire to the winch * Tie base of weights to the end of the string * Clam the motor to the end of the bench * Set up the circuit as shown in the diagram * Check with teacher that it is correct * Start with lowest weight and increase until all ten weights have been used * Time how long each weight takes to reach the top of the bench * Then repeat the experiment twice more * Measure the string to see if any increase in size * Then record results on to a table * Then using those results plot a graph My results table will look similar to the following: The efficiency of the motor W/n I/A V/V T/s IVT WH Efficiency 0.1 1. 2. 3. Average: Sensitivity: Make the string as long as possible, if I double the size it will have twice less the error in recording time. It is important to try and decrease the error in recording the time as this is the biggest error. The error in recording time is +/- 0.5 seconds. This error could be decreased if it was being done using a mechanical device but as I am controlling it myself the human error is large. I will measure the length to the length of the worktop so the length is maximised. Adding each weight gradually, having recordings for each weight 3 times therefore diving the error by three. Voltmeter and Ammeter flickers therefore less accurate. Therefore more likely to obtain anomalous results. Resistance in leads cause possible errors as less accurate measurements of voltage and current. Small weights allow weight to be changed and maximum weight can be lifted and can obtain ten results. Strong string, but light and does not get stretched; check the size of string before and after the experiment, so we can see any extension. Thin, so does not overlap on the rotating winch. Averages of recording will help improve accuracy. Plot a graph to show anomalies on a best fit, should show errors or a pattern. Weights might not be accurate weigh them to see if the weight is exact or not. the scales could also be inaccurate therefore hard to make it certain that there is less chance of error. AS Level Experiment Hermanjit Virk 12WSI Electric Motor Efficiency Coursework Observation and Results Results: The efficiency of the motor W/N I/A V/V t/s IVt WH Efficiency % 0.1 1.29 4.56 1.0.5 2.0.48 3.0.42 Average: 0.47 1.29 x 4.56 x 0.47 = 2.764728 = 2.76 0.1 x 0.9 = 0.09 0.09 / 2.76 = 0.032552931 x 100 = 3.26 0.2 1.29 4.56 1.0.50 2.0.53 3.0.58 Average: 0.54 1.29 x 4.56 x 0.54 = 3.176496 = 3.18 0.2 x 0.9 = 0.18 0.18 / 3.18 = 0.056666213 x 100 = 5.66 0.3 1.29 4.56 1.0.59 2.0.64 3.0.60 Average: 0.61 1.29 x 4.56 x 0.61 = 3.588264 = 3.59 0.3 x 0.9 = 0.27 0.27 / 3.59 = 0.075245299 x 100 = 7.52 0.4 1.29 4.56 1.0.66 2.0.70 3.0.67 Average: 0.68 1.29 x 4.56 x 0.68 = 4.000032 = 4.00 0.4 x 0.9 = 0.36 0.36 / 4.00 = 0.08999928 x 100 = 9.00 0.5 1.29 4.56 1.0.72 2.0.77 3.0.75 Average: 0.75 1.29 x 4.56 x 0.75 = 4.4118 = 4.41 0.5 x 0.9 = 0.45 0.45 / 4.41 = 0.101999184 x 100 =10.20 0.6 1.29 4.56 1.0.87 2.0.79 3.0.82 Average: 0.82 1.29 x 4.56 x 0.82 = 4.823568 = 4.82 0.6 x 0.9 = 0.54 0.54 / 4.82 = 0.1119503239 x 100 = 11.20 0.7 1.29 4.56 1.0.84 2.0.88 3.0.94 Average: 0.89 1.29 x 4.56 x 0.89 = 5.235336 = 5.24 0.7 x 0.9 = 0.63 0.63 / 5.24 = 0.120336116 x 100 = 12.02 0.8 1.29 4.56 1.1.00 2.0.96 3.0.92 Average: 0.96 1.29 x 4.56 x 0.96 = 5.647104 = 5.65 0.8 x 0.9 = 0.72 0.72 / 5.65 = 0.12749898 x 100 = 12.74 0.9 1.29 4.56 1.1.01 2.1.05 3.1.02 Average: 1.03 1.29 x 4.56 x 1.03 = 6.058872 = 6.06 0.9 x 0.9 = 0.81 0.81 / 6.06 = 1.336882509 = 13.37 1.0 1.29 4.56 1.1.06 2.1.09 3.1.11 Average: 1.09 1.29 x 4.56 x 1.09 = 6.411816 = 6.41 1.0 x 0.9 = 0.90 0.90 / 6.41 = 1.403658496 = 14.04 See graphs. AS Level Experiment Hermanjit Virk 12WSI Electric Motor Efficiency Coursework Interpretation and Evaluation Conclusion: As you can see from my results my prediction was correct, as you increase the weight on the motor it will have to do more work. As the voltage and current remained constant the efficiency became higher with the more weights that were placed on to the string to be lifted. Due to fact that the motor had to do more work, the time increased resulting in a positive gradient through my graph. Obviously the time was not as accurate as I would have hoped as the motor picked little weights quickly over short distances. The efficiency for the motor in this experiment was quite low, so not much of the energy put in was used usefully. The highest efficiency reached in my results was when picking up the top weight of 1N, which my calculations showed to have the efficiency of 14.04%, this means that 86.06% was wasted energy; this was probably due to the friction of moving parts in the motor resulting in heat and sound released into the environment. Evaluation: My experiment went reasonably well, I repeated my results three times this increased the amount of accuracy in the experiment, it helped divide error in time by three. I followed my plan making sure of safety and went through my method before conducting the experiment. The biggest error in the experiment as I have previously discussed was time, so it was unlikely that any one could have had results that were perfect. Other errors in my experiment were caused by practical faults, or by a more technical reason. The voltmeter and ammeter persistently changed value in the experiment; therefore we can tell that maybe some resistance was carried in the connecting leads. If I was to test again, I would change the timing technique by using a light gate instrument. To use the light gate instrument I would place the weight at the start when it starts to moving towards the motor it will pass a sensitive sensor that then turn the time of through some kind force mechanism. This could divide the human error by about ten. If I could repeat the test I would test the affect of voltage on the efficiency, and I would use one set number of weights. This test would probably show us a decrease in efficiency as the voltage is increased. AS Level Experiment Hermanjit Virk 12WSI Lens Coursework Plan Aim: In this investigation, I will be changing the factors of object distance and image distance, to find the focal length of a converging lens. Apparatus: Converging Lens (2, plus combination of both) Blue Tack Light Box Lens Stand Power Supply Ruler Screen Tape (Scissors) Diagram: Safety: In this experiment it is important to consider the safety aspects when carrying out this practical task; I will make sure of the following things before starting the experiment: * Equipment correctly setup (Above diagram), avoiding confusion, less chance of accidents. * Make sure that the leads from light box are working in order * The Power supply is working, and the voltage is not exceeding the limit * Check the circuit before starting and be standing during the experiment * Lens should be affixed firmly with blue tack to the Lens stand, no chance of breaking * Light box working and in order, light should be bright and clear * Do not look directly into the bright light, where safety goggles * Work top should be cleared of any objects which are not being used in the experiment * Apparatus should be spread out neatly and spaciously Keeping the same Changing Ruler Position/Measurement Points Object Distance (u) Voltage Image Distance (v) Light Bulb Lens (2 converging lenses, both lenses together for one set of results) Material of lens Variables: Theory: In this experiment we will be using converging lenses, any lens that is fatter at the centre than at its edges will converge. (Below) We can see a parallel beam converging through a point, F known as the principle focus of the lens. The distance from the lens to this point is called the focal length, f, of the lens. The power of a lens, P (the unit for the power of a lens is dioptre, D), can also be measured, which is the reciprocal of the focal length in metres: P = 1/f When a lens converges light, it carries with it an image of the source object correct in every detail. This can then be projected on to a screen, this is a real image. To get the clearest image the object distance (u), and image distance (v), must be exactly proportional to the focal length (f), (Previous diagram). The equation connecting the distance of an object from the lens and the distance for its image is: 1/f = 1/u + 1/v The focal length of converging lenses are positive, therefore the images produced are of real objects and images not virtual which can be produced by diverging lenses. Material of the lenses is a factor in this experiment but as I will be using glass it is important to know what effect this has on the lens and image. The material of the lens will not be changing. Glass is a clear transparent material and that is one of the reasons it is being used. Glass is harder than plastic therefore it does not scratch easily and it can then help produce a clear image. The material does not easily deform therefore the focal point can remain constant. Glass is good at transmitting light; it absorbs very little. The problem however is that glass reflects a proportion of the light. It reflects about 10% of the light this can be reduced by adding a anti-reflection coating to the lens. This increases the transmission of light up to 99% making the image brighter. Prediction: The fatter in the middle, out of the two lenses that I decide to use, the smaller the focal length. Therefore if one of the lenses is twice as fat in the middle compared to the other. Its focal length will be twice as short, because it will refract light at a doubly greater angle. Therefore I will be able to have a larger range of results with a fatter lens as image will appear earlier and take longer to fully deform. Therefore when both lenses are combined the focal length will obviously be smaller than that of both lenses in proportion. When I increase the size of the object distance (u, to then obtain a clearer picture I will probably have to decrease the size of v by a proportional amount if I would like to attain a clear picture. Therefore if I double the distance of object distance (u), I will have to therefore decrease the image distance by a proportional extent, to acquire a fine focus of the image. Therefore as I increase the length of both object distance (u) and the image distance (v), the picture will gradually become more distorted until it is no longer a real image. It is important that both the lenses are the same material if I want to obtain a good set of results. Both lenses should be transparent and have minimal scratches to prevent image being unclear. The lens must also be hard so it does not easily get affected in any form during the experiment, so there is less chance of the results being anomalous. Both lenses should not be deformed in shape or any other way, as this could affect the focal point from remaining constant. Method: In this practical I am going to change the object distance (u) and the image distance (v), to two different converging lenses. I will do this by planning out how I will conduct the experiment: * Clear the work top * Setup the power supply and connect the ray box * Blue Tack the metre rule to the work top, making sure it is secure * Set the lens stand in front of the ray box * Setup the screen in front of the lens stand * Calculate the focal length of the lens, by using parallel light from a window * Blue Tack the lens into the lens stand making sure it is secure * Switch on the power supply and gradually maximise the voltage * Stick tape on to side of ray box, lens and screen from were I will measure from and to * Using a setsquare measure the middle of the lens and check that all equipment is set out parallel, avoiding errors in measurements * Vary distance of object distance(u) and image distance (v) until I get a large range of well spaced results, I will repeat my readings so that I can obtain an average * Increase the lengths of both object distance(u) and image distance (v) until there is no longer a real image, increasing the length by 0.5 2.0 cm each time * Record my results in a table, It should be clear and informative, it should state any units * Plot my results onto a graph * The table will have ten results for both lenses, and the combination of both lenses, having a column for object distance (u), image distance (v), and the calculation of focal length (f), using the equation: 1/f = 1/u + 1/v My results table will look similar to the following: Lens (Focal length (cm), measured using parallel light) Object Distance/ u (cm) [1/u] Image Distance/ v (cm) [1/v] Focal Length (cm) 1/f = 1/u + 1/v 1 () Average: 2 () Average: 1;2 Combined () Average: Sensitivity: In this experiment it is important that I am aware of errors; I can decrease the amount of inaccuracies by checking the sensitivity of my practical when measuring and recording: To measure the lengths of object distance (u) and image distance (v), I will be using a metre rule and slowly increasing the lengths of both. The error in reading from a metre ruler in each reading is +/-0.5mm therefore the error in accuracy is +/-1mm. The error of a metre rule can be overcome and decreased by using a vernier callipers which would help divide the error by ten times, the error being +/-0.1mm. If more accuracy was needed a micrometer could be used which in fact is ten times more accurate then a vernier. It will also be important to make sure that the ruler is straight as well as any other equipment when measuring, and not at an angle. This could cause an error in the distance being measured. To overcome this I may use a setsquare to line up the equipment. With a ruler I might decide to place, it directly parallel to the end of the bench, and blue tack it firmly down. I could also use the setsquare to measure the middle of the lens so it is clear to see where I am measuring from. I will take a range of ten readings and make an average of three results for each reading therefore improving my results dividing the error by three. This then gives more accurate table of results. Errors could also happen if the lenses are scratched, if one is scratched more than the other it will therefore transmit less light and cause errors in my results. That is why it will be important to pick lenses that are similar in shape and only different in size. AS Level Experiment Hermanjit Virk 12WSI Lens Coursework Observation and Results Results: Lens (Focal length (cm), measured using parallel light) Object Distance/ u (cm) [1/u] Image Distance/ v (cm) [1/v] Focal Length (cm) 1/f = 1/u + 1/v Significant figures 1 (15.5) 19.2 [0.052083333] 26.0 [0.038461538] 32.9 [0.030395136] 39.7 [0.025188916] 46.6 [0.021459227] 53.4 [0.019026591] 60.3 [0.017083747] 67.1 [0.015003129] 74.0 [0.014013513] 80.8 [0.012376237] 80.8 [0.012376237] 38.5 [0.026074025] 29.4 [0.034013605] 25.5 [0.039215686] 23.3 [0.043018454] 21.9 [0.046062100] 20.9 [0.048046889] 20.2 [0.050004950] 19.6 [0.051020408] 19.2 [0.052083333] 15.513600230345936220 15.520380190718594327 15.530842990782881473 15.530840768304103486 15.533333671960007382 15.530677584360272210 15.520566955136062917 15.530002568715020987 15.500726658232962476 15.513600230345936220 Average:15.52 cm 2 (13.5) 16.1 [0.062111801] 23.6 [0.042372881] 31.2 [0.032051282] 38.7 [0.026039793] 46.2 [0.022045021] 53.8 [0.019087360] 61.3 [0.016313213] 68.8 [0.015034883] 76.4 [0.013089005] 83.9 [0.012018951] 83.9 [0.012018951] 31.6 [0.032045569] 23.8 [0.042016806] 20.8 [0.048076923] 19.1 [0.052356020] 18.0 [0.056055555] 17.3 [0.058003468] 16.8 [0.060023809] 16.4 [0.061075609] 16.1 [0.062111801] 13.510900068339168026 13.510145105713507916 13.501091050169946334 13.530739561427485496 13.513323413923325754 13.490465390320841850 13.492239351624501372 13.50280396526581916913.510900068339168026 Average: 13.51 cm 1;2 Combined (7.5) 08.2 [0.122051219] 17.5 [0.057142857] 26.8 [0.037313432] 36.1 [0.028000831] 45.4 [0.022026431] 54.6 [0.018315018] 63.9 [0.016049452] 73.2 [0.014061202] 82.5 [0.012121212] 91.8 [0.011093246] 91.8 [0.011093246] 13.1 [0.076335877] 10.4 [0.096153846] 09.5 [0.105263157] 09.0 [0.111111111] 08.7 [0.115042528] 08.5 [0.118047058] 08.4 [0.119047619] 08.3 [0.120481927] 08.2 [0.122051219] 7.5306000396403418087 7.4918301217930340874 7.4924731738366612976 7.5208333853524309154 7.5110294585429555249 7.5042654620099337564 7.5020718847027577841 7.5452941309003114420 7.5412996067913595922 7.5306000396403418087 Average: 7.52 cm See graphs. AS Level Experiment Hermanjit Virk 12WSI Lens Coursework Interpretation and Evaluation Conclusion: As we can see from my results the fatter in the middle, out of the two lenses that I decided to use, the smaller the focal length. This is because the lens refracts light at a greater angle. Therefore I will have a large range of results with a fatter lens as image will appeared earlier and took longer to fully deform. Therefore when both lenses were combined the focal length was being smaller than that of both lenses in proportion, as I had earlier predicted. When I increased the size of the object distance (u), to obtain a clear picture, I had to decrease the size of v by a proportional amount. Therefore when I increased the length of both object distance (u) and the image distance (v), the picture gradually became more distorted until it was no longer a real image. It was important that both the lenses were the same material as I wanted to obtain a good set of results. Both lenses were transparent and had minimal scratches to prevent image being unclear. The lens was also hard so it did not easily get affected in any form during the experiment, so there was less chance of the results being anomalous. Both lenses were not deformed in shape or any other way, the glass material was not deformed so it did not affect the focal point from remaining constant. Evaluation: I could have done the experiment differently by measuring the distances more accurately, for example the focal length as then I could have see how accurate my results were. To have done this I might have used a vernier calliper, which could have helped divided errors by ten times. I could have also have improved my experiment by checking the measuring points more carefully and this would have made the difference in accuracy. Using a setsquare to measure the middle of the lens was not as accurate as I would have hoped as the stand was where I eventually measured from because the ruler was in a fixed position. I also had anomalies as combining lenses probably was not that accurate as the glass was still separate from each other and maybe the results were inaccurate due to this. It was hard to choose the position to measure the light from as it was hard to be accurate in choosing where the light started as the bulb was covered from the sides as it was in a ray box. In think if I was to do this experiment over I would use a larger range in the lenses as it would have given me a better range of results, and when combining the lenses using something to hold them tight. I would have also spent more time in using a different measurements if the lenses could have produced a larger range of results.