Conductivity

Conductivity - Chemistry 124 Name: Partner : Fall 2010...

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Chemistry 124 Fall 2010 Dr. Heying Name: Anthony Atchley Computer #: 28 Partner : Kyle Jackson Conductivity: LED Experiment Instructions: Each person is to submit an individual report after performing the experiment. This report is due at the beginning of class on Monday, November 8 th . You are to fill in the appropriate spaces using Microsoft Word to create a clear and informative report. Be sure to keep your answers and graphs within the allotted spaces (some resizing may be necessary on your part). You will turn in a hard copy of this report. Part 1: Temperature Dependence of Resistance, R, of a Metal In the table below, record the results of your measurements of resistance for each temperature you recorded. Be sure to title your table appropriately . Temperature to Resistance Observation Table Temperature Resistance ( ) Room Temperature 157 Cold Temperature 26 1. Describe what you observed, i.e., how does resistance change with temperature? Explain why resistance of a metal changes as it does with temperature. As the Metal was chilled by liquid nitrogen it turned super cold and completely froze. The resistance rapidly declined at this extremely cold state compared to the constant higher resistance at room temp. The resistance of the metal declines in cold due to the near perfect lattice of the atoms with little vibrations which allows electrons to flow through unhindered. At room temperature, the atoms have more movement with more particle vibrations the electrons must navigate through a non- linear path making in harder to get through.
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Chemistry 124 Fall 2010 Dr. Heying
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Chemistry 124 Fall 2010 Dr. Heying Part 2: Band Gap of a Compound Semiconductor LED: Effect of Composition In the table below, record the results of your observed values of voltage and color and your calculated values for the energy and wavelength. Be sure to title your table appropriately . LED Observations vs. Phosphorus Content Table LED Composition P content, in % Measured Voltage Observed Color Energy, J Wavelength GaP 1.00 As 0.00 100 1.96 Green 3.14x10 -19 633 GaP 0.85 As 0.15 85 1.90 Yellow 3.04x10 -19 654 GaP 0.65 As 0.35 65 1.87 Orange 2.99x10 -19 664 GaP 0.40 As 0.60 40 1.74 Red 2.79x10 -19 712 Show a sample calculation of each of the following: 1. Energy in J Volts x 1.602x10^-19 = Joules
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This note was uploaded on 11/13/2011 for the course CHEM 124 taught by Professor Hascall during the Fall '08 term at Cal Poly.

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Conductivity - Chemistry 124 Name: Partner : Fall 2010...

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