ConductivityLEDExperiment

ConductivityLEDExperiment - Chem 124 Fall 2007 Dr. Berber...

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Unformatted text preview: Chem 124 Fall 2007 Dr. Berber Name: Computer #: Partner : Chem 124 Fall 2007 Dr. Berber Conductivity: LED Experiment Part 1: Temperature Dependence of Resistance, R, of a Metal Resistance of Choke Coil with Temperature Change Temperature Resistance ( ) Room Temperature 163.0 Cold Temperature 23.8 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 temperature decreased, so did the resistance. As the temperature goes down so does the random activity of the atoms in the metal, so the electrons have more room to move around and cross the band gap. Part 2: Band Gap of a Compound Semiconductor LED: Effect of Composition LED Composition Observations & Calculations LED Composition P content, in % Measured Voltage Observed Color Energy, kJ Wavelength GaP 1.00 As 0.00 100% 2.109 V Green 3.379X10-21 kJ 588 nm GaP 0.85 As 0.15 85% 1.929 V Yellow 3.090X10-21 kJ 643 nm GaP 0.65 As 0.35 65% 1.913 V Orange 3.065X10-21 kJ 649 nm GaP 0.40 As 0.60 40% 1.801 V Red 2.885X10-21 kJ 689 nm Show a sample calculation of each of the following: 1. Energy in kJ E= V X (1.602 X10-21 kJ) E= (2.109)(1.602 X10-21 kJ)= 3.379X10-21 kJ 2. Wavelength in nm E = hc = hc E =[(3.00X10 8 m/s)(6.626X10-34 J/s)]/ (3.379X10-21 kJ)(10 9 nm/1m) Chem 124 Fall 2007 Dr. Berber 3. How does the energy of the light emitted change as a function of phosphorus content? Suggest an explanation for this observed behavior....
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ConductivityLEDExperiment - Chem 124 Fall 2007 Dr. Berber...

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