This is my first laboratory report in Phy12L; Prof Ricardo De Leon's format....
MAPUA INSTITUTE OF TECHNOLOGY Department of Physics E301: LINEAR EXPANSION
BUNDALIAN, Patrick John Edbert G.
[email protected]/2010140216/CPE-3 PHY12L-A1 Group 3
SCORE Computation (10)
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Data Sheet (5)
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Results and Discussion (25)
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Conclusions (25)
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Error Analysis (10)
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Presentation (10)
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Graphs/Figures/Tables (15)
July 27, 2015
TOTAL x 0.7
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PERFORMANCE
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E301: LINEAR EXPANSION BUNDALIAN, Patrick John Edbert G.
OBJECTIVE The experiment was carried out with the intention to determine and compare the coefficient of linear expansion of the aluminum and copper tubes and to determine the factors affecting the change in length in the thermal expansion phenomena. The study was conducted as the water inside the steam generator was heated up to the boiling point. The steam produced travelled from the steam generator to the metal tube thru a rubber tubing which connected the generator onto one end of the metal tubes. Changes in length, changes in temperature, and resistance were all considered to arrive with a value for the coefficient of linear expansion of the two metal rods. The temperature of the environment (in this case the laboratory) directly affected the actual value of the coefficient of linear expansion.
Fig1. (a) Aluminum tube, (b) copper tube, (c) digital multi tester, (d) expansion base with thermistor, and (e) steam generator.
into the slot of the mounting block pressing against the spring arm of the dial gauge. We then attached the thermistor lug onto the middle of the tube locked by a thumb screw. Maximum contact between the lug and the tube was achieved. The leads of the ohometer were inserted into the plug connector of the tube where we obtained the resistance of the thermistor at room temperature and the initial temperature of the metal tube was recorded. (Please see figure 2)
MATERIALS AND METHODS The following materials were used to carry out the process in obtaining a value for the coefficient of linear expansion of the aluminum tube and the copper tube respectively. (Please see figure 1) For the first part of the experiment, we measured the initial length of the metal tube from its inner edge up to the inner edge of the angle bracket of the expansion base. Consequently, we mounted the metal tube onto the expansion base – we made sure that the pin on the edge of the tube fitted
Fig2. Obtaining the initial temperature of the aluminum tube.
We then turned the outer casing of the dial guage to align the zero point on the scale with the indicator needle. (Please see figure 3)
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Fig3. Dial gauge aligned to zero.
After setting up the steam generator (and after heating the water up to the boiling point) we then attached the rubber tube onto the end of the steam generator and onto one end of the metal rod. (Please see figure 4)
Fig4. Steam from the generator flowed into the rubber tube and was then introduced into the metal tube.
As the steam began to flow, we observed the movement of the dial gauge and noticed that the hand moved counterclockwise. As soon as the thermistor resistance stabilized, we recorded the resistance. The expansion of the tube length (∆L) as indicated by the displacement of the indicator on the dial gauge. (Please see figure 5) Obtaining the data required to arrive with a feasible value for the experimental coefficient of linear expansion, we proceeded with the math and came up with acceptable result which varied (greatly) in contrast to the theoretical value due to the room temperature of the laboratory.
Fig5. Observing and noting the changes reflected on the dial ensued by the flowing steam.
OBSERVATIONS AND RESULTS Due to the cool temperature of the setting, the experimental value of the results did not bode well with the supposed results we should have obtained seeing the percent error. Acquiring the final resistance became a minor struggle because of the inability of the digital multi tester to present an accurate and precise value – to obtain it, we simply averaged the final five values presented to us in its slowest succession eliminating the possibility of obtaining a potentially higher percentage of error. The table below shows the variation of properties concerning the linear expansion of the aluminum tube and the copper tube. The table also exhibits the calculated percentage of error of the experimental value as opposed to the actual value of the coefficient of linear expansion.
Trial/Type of Tube
Aluminum Tube
Copper Tube
Initial Length of the Tube, Lo
703mm
704mm
Initial Resistance of Thermistor at Room Temperature, Rrm
94.3kΩ
92.2kΩ
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Initial Temperature, trm
26oC
27oC
Change in Length of Tube, ∆L
1.18mm
0.875mm
Resistance of Thermistor at Final Temperature, Rhot
11.41kΩ
10.17kΩ
Final Temperature of the Tube, thot
79oC
82oC
Change in Temperature of the Tube, (thot-trm)
53oC
55oC
Experimental Coefficient of Linear Expansion, αexperimental
3.16702E05/oC
2.25981E05/oC
Actual Coefficient of Linear Expansion, αactuall
2.38E-05/oC
1.68E05/oC
Percentage of Error
33.068069%
34.51274%
materials who and which helped me accomplish this work with only few notable encountered difficulties – and typing the entirety of this work being the first. I won’t be a hypocrite not to acknowledge my groupmates’ small talks on how they’ll do their paper (gave me an idea on how I’ll do mine), Ma’am Novida’s lecture especially the part where she talked about how gasoline will spill in a steel barrell if thermal expansion is not observed, Sir De Leon’s meticulous introduction and instructions, and the unubuiquitous feeling of guidance from above – you just know you’re favored. Here the links of my trusted pages: [1]http://www.asminternational.org/docu ments/asmreadyreference/ [2]http://www.aplusphysics.com/courses/ honors/thermo/expansion.html [3]http://www.owlnet.rice.edu/~msci301/ ThermalExpansion.pdf
DISCUSSION & CONCLUSION When a material is exposed to different temperature change, it is subjected to either expand or contract. Changes in its dimensions can at times be noticed most especially if the object’s coefficient of linear expansion (in this case coined as volumetric temperature expansion coefficient) is exceptionally high (eg. Gasoline). However, since most of the time people only observe objects which has less coefficient of linear expansion (eg. Frying pan), seeing changes ensued by the surrounding’s temperature with the naked eye is nearly as impossible as hearing a disturbed spider squirming with your own ears. ACKNOWLEDGEMENT & REFERENCE This paper is not fully my brainchild. So I give full credence to the people and written
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