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# 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.

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Introduction

AS Level Experiment                                                                             Hermanjit Virk 12WSI

Electric Motor Efficiency Coursework

Plan

Aim:        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.

Apparatus:        Ammeter

Crocodile Clips

G Clamp

Motor

Power Supply

Ruler/ Scissors/ Tape

Stop Watch

Variable Resistor

Voltmeter

Weights

Wire

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:

• 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 CurrentLength of string /Height TemperatureVoltageMotor 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

Middle

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

Conclusion

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.

This student written piece of work is one of many that can be found in our AS and A Level Microscopes & Lenses section.

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