EECS 100 B Boser Multimeter and Supplies LAB REPORT Lab Session Name 1 SID Name 2 SID 1 Laboratory Power Supply Set the laboratory supply for 5V output and 20mA maximum current and load it with resistor R1 1k Figure 1 Use the 0 25V output Figure 1 Power supply with resistive load and voltmeter a Verify the output voltage with the voltmeter Use the multimeter for all these measurements The meter that is built into the supply is not as accurate Predicted value V of 1 P Measured Value V of 1 M b Disconnect the voltmeter What is the current flowing through resistor R1 Predicted value A of 1 P Design a circuit for measuring the current flowing through R1 Your diagram should include the supply resistor and the ampere meter of 3 P Page 1 of 7 EECS 100 Multimeter and Supplies B Boser A of 1 M Measured Value Explain discrepancies of 2 M c Replace R1 with a 100 resistor What are the voltage across and current flowing through the resistor Predicted values V A of 2 P Measured values V A of 1 M Explain discrepancies of 2 M d Calculate the smallest value of R1 for which the supply output remains at 5V Calculated value of R1 of 2 P Measured voltage and current note that the resistor gets warm or hot if you increase the voltage V A Explain discrepancies of 2 M of 2 M e Measure the IV characteristic of the supply with the settings from part a using different values of R1 to get sufficient data points Also transfer the measured data points from parts b c and d to the Page 2 of 7 EECS 100 B Boser Multimeter and Supplies graph Please draw neatly and use a ruler of 3 P of 3 M 2 Solar Cell A solar cell is another form of an electrical supply that does not draw its energy from burning coal or chemical reactions but from the sun or other light source We will characterize a small solar cell and assess its suitability as an alternative energy source a Load the solar cell with a 1k resistor and measure the voltage across and the current though the resistor Figure 2 Experiment with different light exposures and try to maximize the power delivered by the solar cell to the resistor P IV Record the maximum power along with the corresponding values for voltage and current and the distance between the solar cell and the lamp V A R1 V solar cell mW Page 3 of 7 A Figure 2 Solar cell test circuit cm of 4 M EECS 100 Multimeter and Supplies B Boser b Calculate the power per area of the solar cell For comparison high efficiency solar cells in direct sunlight generate about 120W m2 Try using a solar cell outside on a sunny day to see if you can match this result play with R1 to maximize the power W m2 Power per area of 1 M c What area solar cell is required to power a 25W fluorescent bulb High efficiency solar cell m2 of 1 P Laboratory solar cell m2 of 1 M d Using as best as possible the same light expose that yielded the maximum output power in part a measure the IV characteristic of the solar cell by connecting different valued resistors to it Be sure to test resistance values from 10 to 1 k Collect your results in the table below and plot them in the current and voltage graphs below Choose different resistors including parallel and series combinations of available resistors to get a sufficient number of points so that you can accurately interpolate in the graphs between measurements and accurately determine the peak power available from the solar cell You may notice some variation in the measured current This may be due to varying illumination or heating of the solar cell the efficiency of solar cells drops with increasing temperature a problem for solar farms installed in warm climates R1 V I P IxV Peak power delivered by solar cell mW of 1 M Voltage at peak power V of 1 M Load resistance at peak power of 1 M Page 4 of 7 EECS 100 Multimeter and Supplies B Boser of 10 M Page 5 of 7 EECS 100 Multimeter and Supplies B Boser SUGGESTIONS AND FEEDBACK Time for completing prelab Time for completing lab Please explain difficulties you had and suggestions for improving this laboratory Be specific e g refer to paragraphs or figures in the write up Explain what experiments should be added modified how or dropped Page 6 of 7 EECS 100 Multimeter and Supplies B Boser PRELAB SUMMARY Summarize your prelab P results here and turn this in at the beginning of the lab session Problem 1a 1b 1b Result V A 1c V A 1d 1e m2 2c Page 7 of 7
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