Thermal expansion lab procedure

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Physics I: Thermal Expansion Worksheet Class: Section: Lab Group: Assignment Date: Names: answer key: Copper Steel Aluminum Length (mm) ΔL (mm) 701 701 701 .885 .500 .678 Table 1: Data and Calculations Room Resistance at Resistance Room Temp. when Heated Temperature T rm ( C˚ ) R rm (Ω) R hot (Ω) 116200 7780 22 114100 8870 22 113800 8900 22 Table 2: Results Copper Steel Aluminum Experimental Thermal Coefficient α (1/C˚) Accepted Thermal Coefficient α (1/C˚) % Error (%) 0.000018 0.000011 0.000015 0.0000176 0.0000113 0.0000215 2.3 2.6 30 Worksheet numbers data Heated Temperature T hot ( C˚ ) 90 86 86 Change in Temperature Δ T ( C˚ ) 68 64 64 ons Thermal Expansion Apparatus 012-04394C Accepted Values for Coefficient of Thermal Expansion Material a ( x10-6/∞C ) Copper 17.6 Steel 11.3 to 13.5 Aluminum 23.4 Replacement Parts The following parts can be ordered from PASCO scientific. Item Changing Tubes ➤ Caution: Tube When changing tubes be careful not to pull the wires off the thermistor. The thumbscrew must be completely removed before the thermistor can be lifted off the threaded rod. Thermistor Thumbscrew 2 PASCO Part # mod. Thermistor (100 kΩ) 150-03140 Al Tube Assy 003-04413 Cu Tube Assy 003-04412 Steel Tube Assy 003-04414 Foam Insulator 648-03100 Dial Gauge 620-050 012-04394C Thermal Expansion Apparatus Experiment: Measuring the Coefficient of Linear Expansion for Copper, Steel, and Aluminum Introduction Most materials expand somewhat when heated through a temperature range that does not produce a change in phase. The added heat increases the average amplitude of vibration of the atoms in the material which increases the average separation between the atoms. Suppose an object of length L undergoes a temperature change of magnitude ∆T. If ∆T is reasonably small, the change in length, ∆L, is generally proportional to L and ∆T. Stated mathematically: ∆L = αL ∆T; where α is called the coefficient of linear expansion for the material. For materials that are not isotropic, such as an asymmetric crystal for example, a can have a different value depending on the axis along which the expansion is measured.