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# Holmes / A2 / Lab Design

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### Holmes / A2 / Lab Design

1. 1. Physics Experiment Presentation <ul><li>by ZCHHolmes </li></ul><ul><li>from AⅡ1 </li></ul>
2. 2. Introduction <ul><li>A manufacturer of filament lamps for use as a night light in children’s bedrooms is concerned about the surface temperature of the glass envelope after the lamp has been left on for some time. The surface temp must not be too high, otherwise danger of burns or fire resulting from accidental contact with the surface of the lamp. However, it is important that the power output from the lamp should not be too small; otherwise lamp will be too dim to be useful. </li></ul>
3. 3. CONTENTS <ul><li>Introduction </li></ul><ul><li>Topic </li></ul><ul><li>Theory </li></ul><ul><li>Experiment (PartⅠ) </li></ul><ul><li>Experiment (PartⅡ) </li></ul><ul><li>Experiment (PartⅢ) </li></ul><ul><li>Experiment (PartⅣ) </li></ul><ul><li>Data Evaluation </li></ul><ul><li>Safety Precaution </li></ul><ul><li>Improvement </li></ul><ul><li>Bibliography </li></ul>
4. 4. Topic: To investigate how the surface temperature of the glass envelope of a filament lamp varies with electrical power delivered to the lamp.
5. 5. Theory <ul><li>Law of conservation of energy: Energy cannot be created of destroyed. It can only be converted from one form to another. </li></ul><ul><li>Hence the energy input can be divided into the luminous energy and the heat. (ignore other energy lose, e.g. the evaporations of the lamp wick.) </li></ul>
6. 6. Theory <ul><li>Joule’s Law / Joule’s Effect: The rate of heat production by a steady current in any part of an electrical circuit that is proportional to the resistance and to the square of the current, or, the internal energy of an ideal gas depends only on its temperature. Q = I 2 Rt P = I 2 R </li></ul>
7. 7. Theory <ul><li>The theory of thermal energy: △Q = cm△T. </li></ul><ul><li>The theory of luminous intensity: E = I v *Sr*s P = I v * Sr </li></ul>
8. 8. Equipment Part Ⅰ Part Ⅳ Part Ⅱ Part Ⅲ <ul><li>A.C. Power </li></ul><ul><li>Ampere meter </li></ul><ul><li>Voltmeter </li></ul><ul><li>Testing Bulb </li></ul><ul><li>Slide Wire Rheostat </li></ul><ul><li>Stopwatch </li></ul><ul><li>Al sheet </li></ul><ul><li>Calorimeter with thermometer </li></ul><ul><li>Balance </li></ul><ul><li>Water </li></ul><ul><li>Infrared Thermometer </li></ul><ul><li>Candela meter </li></ul><ul><li>Ruler </li></ul>
9. 9. Experiment <ul><li>Part Ⅰ </li></ul><ul><li>Connect the equipments as shown. </li></ul><ul><li>Turn on the A.C. Power, record the readings of ampere meter and voltmeter after 5min (when the testing bulb is in its working condition) as I and V. </li></ul><ul><li>Change the resistance by the various resistor until get at least 6 sets of data. </li></ul><ul><li>Evaluate the data use the formula R=V/I, calculate the resistance of the testing bulb R 0 </li></ul><ul><li>Use the thermometer to measure the room temperature as T r . </li></ul>
10. 10. Experiment <ul><li>Part Ⅱ </li></ul><ul><li>Connect the equipments as shown. </li></ul><ul><li>Turn on the A.C. Power, record the readings of ampere meter and voltmeter after 5min (when the testing bulb is in its working condition) as I and V. </li></ul><ul><li>Record the time taken of turning on the bulb as t. </li></ul><ul><li>Measure the mass of the Al sheet as m s. </li></ul><ul><li>Cover the testing bulb with the Al sheet as much as possible. </li></ul>
11. 11. Experiment <ul><li>Part Ⅱ </li></ul><ul><li>Measure the mass of the empty Al Beaker as m b . </li></ul><ul><li>Put some water in the beaker, and measure the mass of the Al Beaker with the water as m c . </li></ul><ul><li>Use the thermometer to measure the temperature of the water as T o . </li></ul><ul><li>Take the Al sheet into the water and set the Al beaker into the cover (calorimeter). </li></ul><ul><li>Use the thermometer to measure the temperature of the water as T f . </li></ul><ul><li>Use the Slide Wire Rheostat to change the power input to get at least 6 sets of data and calculate the average value. </li></ul><ul><li>Evaluate the data. </li></ul>
12. 12. Experiment
13. 13. Experiment <ul><li>Part Ⅲ </li></ul><ul><li>Connect the equipments as shown. </li></ul><ul><li>Turn on the A.C. Power, record the readings of ampere meter and voltmeter after 5min (when the testing bulb is in its working condition) as I and V. </li></ul><ul><li>Use the Infrared Thermometer to measure the temperature of the surface as T s . </li></ul><ul><li>Use the Slide Wire Rheostat to change the power input to get at least 6 sets of data and calculate the average value. </li></ul><ul><li>Evaluate the data. </li></ul>
14. 15. Experiment <ul><li>Part Ⅳ </li></ul><ul><li>Connect the equipments as shown. </li></ul><ul><li>Turn on the A.C. Power, record the readings of ampere meter and voltmeter after 5min (when the testing bulb is in its working condition) as I and V. </li></ul><ul><li>Use the Candela meter to measure the luminous intensity, I v . </li></ul><ul><li>Use the Slide Wire Rheostat to change the power input to get at least 6 sets of data and calculate the average value. </li></ul><ul><li>Use the balance to measure the mass of the glass of the bulb. </li></ul><ul><li>Evaluate the data. </li></ul>
15. 17. Data Evaluation <ul><li>Part Ⅰ </li></ul><ul><li>R 0 = V/I </li></ul><ul><li>Part Ⅱ </li></ul><ul><li>m Al = m s + m b </li></ul><ul><li>m water = m c – m b </li></ul><ul><li>△ T = T f – T 0 </li></ul><ul><li>P input = I 2 * R 0 </li></ul><ul><li>∵ c Al m s (T S -T r ) = (c Al m a +c water m w )△T </li></ul><ul><li>∴ T s = [(c Al m a +c water m w )△T / c Al m s ] + T r </li></ul>
16. 18. Data Evaluation <ul><li>Part Ⅲ </li></ul><ul><li>P input = I 2 * R 0 </li></ul><ul><li>Part Ⅳ </li></ul><ul><li>P input = I 2 * R 0 </li></ul><ul><li>Q =( P input - I v * sr)*t </li></ul><ul><li>T s = (Q / c glass m glass ) + T r </li></ul><ul><li>(Assume the sr of the 4∏ 2 ) </li></ul>
17. 19. Safety Precaution <ul><li>Wear the safety gloves when touch the testing bulb and the Al sheet. </li></ul><ul><li>Take safety glasses (with dark colour) to prevent the damages on eyes. </li></ul><ul><li>Keep the A.C. power away from the water in part Ⅱ. </li></ul>
18. 20. Improvement <ul><li>Set the testing bulb and the Al sheet in a cover to prevent the heat lose.( the IR thermometer in PartⅢ, the detector of candela meter in PartⅣ) </li></ul><ul><li>Move the Al sheet as quickly as possible in Part Ⅱ. </li></ul><ul><li>Target the surface of the bulb instead of the lamp wick in PartⅢ. </li></ul><ul><li>Use a new bulb to prevent from the effects from the darkness of the vapors of the lamp wick. </li></ul><ul><li>In PartⅣ, use a bulb with relative small base or otherwise calculate the exactly Sr of the bulb. </li></ul><ul><li>Finish the PartⅡ,Ⅲ,Ⅳ to find the average of the experiment. </li></ul>
19. 21. Bibliography <ul><li>http://en.wikipedia.org/wiki/Candela </li></ul><ul><li>http://en.wikipedia.org/wiki/Steradian </li></ul><ul><li>http://www.pemed.com/surgery/lasers/candelameter01_8.jpg </li></ul><ul><li>http://www.daviddarling.info/encyclopedia/J/AE_Joules_law.html </li></ul><ul><li>http://en.wikipedia.org/wiki/Joule's_Law </li></ul><ul><li>http://www.tiptemp.com/assets/17/tipWD-35639-30.jpg </li></ul><ul><li>http://www.tiptemp.com/assets/17/tipWD-35639-30.jpg </li></ul><ul><li>Physics AS/A2 P65-67, P61-62. </li></ul>
20. 22. The End