2. Measurement of the Charge of an Electron Presented by John Cole Experiment Conducted by John Cole, Sarmadi Almecki, and Pirouz Shamszad

3. Abstract

4. Theory Fundamental Charge Townsend Millikan’s Oil Drop Experiment

5. Transistor Theory I c = A[e qV b /kT –1]I c = collector current q = charge (eV) V b = base voltage of the transistor K = Boltzman’s Constant (8.617 342 x 10 -5 eV K -1 ) T = temperature in Kelvins

6. Ohm’s Law V = I RV = voltage (eV) I = current (amps) R = resistance (ohms)

7. Combining the Equations V rc = Be qV b /kT Approximates for the specific voltage greater than 1/40 V

8. Experimental Setup NPN transistor 2N3904 2  10 turn potentiometer Voltage source Voltmeter (base) Voltmeter (rc) Resistors

9. Experimental Setup Temperature was varied in the second part using a heat pump & refrigeration device. Transistor leads were extended so that it could be remotely placed in the temperature controlling device. Mercury thermometer monitored temperature

10. Procedure Part I Voltage was varied using the potentiometer Constant Temperature, Varying Voltage Data was recorded at 294.15K

11. Procedure Part II Constant Voltage, Varying Temperature Temperature was adjusted via heat pump / refrigerator Data was recorded T

12. Part I: Varying Potential Log Scale Logarithmic Scale plotted using gnuplot software

13. Part I: Non Log Scale

14. Interpretation: Part I Slope = q/kt Slope value found using method of least squares Slop value = 31.1452 +/- 1.03 Using the equation V rc = Be qV b /kT k and t are constants, solved for q Fundamental Charge of an Electron 1.2648 e-19 C +/- 4.18 e-21 C

15. Part II: Log Scale

16. Part II: Non Log Scale

17. Interpretation: Part II Slope found using method of least squares Value of 6411.11 +/- 247.8 slope = qV b /k Fundamental Charge of an Electron1.7703 e-19 C +/- 6.842 e-21 C

18. Error Voltmeters »Vc = 1/100 V »Vb = 1/1000 V Statistical Limitations limited data Thermometer Single Degree Accuracy Resistor }} accurate to only 2%

19. Conclusion 1.7703 e-19 C +/- 6.842 e-21 C 1.2648 e-19 C +/- 4.18 e-21 C Part I : Part II: Average 1.3175 e-19C +/- 5.511e-21C

20. Improvement More Accurate Equipment More independent sets of data for statistical improvement Attention to detail in circuit construction Different Transistors