Laboratory Report: Capacitor Charge and Discharge Experiment in Circuit Analysis II - Prof, Lab Reports of Electrical Circuit Analysis

Download Laboratory Report: Capacitor Charge and Discharge Experiment in Circuit Analysis II - Prof and more Lab Reports Electrical Circuit Analysis in PDF only on Docsity! Circuit Analysis II TEET 3145 Laboratory # 3 Capacitor Charge and Discharge Fall 2009 Georgia Southern University   Mechanical and Electrical Engineering Technology Page 1 of 8 Your Name: ________________________ Partner Name: ________________________ Procedure: 1. Before building the circuit measure and record the actual value of the capacitor and resistors that will be used in this experiment. Use the inductance-capacitance-resistance (LCR) meter that is available in the lab. Nominal values: C = 100 μF, R1 = 330 kΩ , R2 = 270 kΩ Measured value: C = Measured value: R1 = R2 = Note: R1 will be used to charge the capacitor. R2 will be used to discharge the capacitor. You will use the measured values of the resistors and capacitors for the calculations. Part A: Charging the capacitor 1. Consider the RC circuit shown in figure 1. Calculate the time constant of the circuit. Use the measured values. τcharge = 2. Before connecting the capacitor verify that the capacitor is completely discharged, do this by placing a low value resistor ( ≈50 Ω) across the capacitor for a few seconds. 3. Build a series circuit consisting of a 12 V DC power supply, a 330 kΩ resistor, and a 100 μF capacitor (see fig. 1). The capacitor is an electrolytic type. The physical construction of an electrolytic capacitor requires that one lead be positive with respect to the other lead. A marking on the case will indicate which lead is minus or plus. Double-check this polarity. A reversed electrolytic capacitor may explode. 4. Before powering up your circuit have ready your watch because you will be measuring the voltage across the capacitor every 5 seconds. 5. Power up your circuit and every 5 seconds, record the voltage across the capacitor (Table1). 6. When working with a partner, one person should watch the clock. The other should record the meter readings. A little practice will help the coordination.   Fig. 1. Charging the Capacitor  Circuit Analysis II TEET 3145 Laboratory # 3 Capacitor Charge and Discharge Fall 2009 Georgia Southern University   Mechanical and Electrical Engineering Technology Page 2 of 8 Note: Indicate the units on all your tables and plots Table 1. Voltage values while charging the capacitor Time in seconds Voltage across the capacitor (Vc) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 Circuit Analysis II TEET 3145 Laboratory # 3 Capacitor Charge and Discharge Fall 2009 Georgia Southern University   Mechanical and Electrical Engineering Technology Page 5 of 8 Part B: Discharging the capacitor To discharge the capacitor that was charged in part A do the following: 1. Calculate the time constant of the discharging circuit (fig.4, SW1 open SW 2 close). Note that R2 is the discharging resistance. Show the formula you use to calculate τ. Indicate the units. τdischarge = 2. Open SW1 as shown in fig.4 to disconnect the power supply from your circuit. 3. Before starting the discharging process have ready your watch because you will be measuring the voltage across the capacitor ever 5 seconds. 4. Connect the discharging resistance R2 (270kΩ) in parallel with the capacitor as shown in fig.4.   Fig. 4. Discharging the Capacitor  5. Record the voltage across the capacitor every five seconds. Indicate the units. Table 3. Voltage values while discharging the capacitor Time in seconds Voltage across the capacitor (Vc) 0 5 10 15 20 25 30 35 40 Circuit Analysis II TEET 3145 Laboratory # 3 Capacitor Charge and Discharge Fall 2009 Georgia Southern University   Mechanical and Electrical Engineering Technology Page 6 of 8 45 50 55 60 65 70 75 80 85 90 95 100 6. Plot the measured result and the calculated result on the same graph. Indicate values and units on the both axes. Figure 5. Discharging the capacitor: measured and calculated voltage values 7. Find the capacitor current based on the capacitor voltage obtained on Table 3, and write your results on Table 4. Explain how do you calculate the current and compare with the results obtained in the Prelab. Indicate the units. Circuit Analysis II TEET 3145 Laboratory # 3 Capacitor Charge and Discharge Fall 2009 Georgia Southern University   Mechanical and Electrical Engineering Technology Page 7 of 8 Table 4. Current values while discharging the capacitor Time in seconds Current through the capacitor (Ic) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 8. Using the values in Table 2, and your results of the PreLab, plot the measured and the calculated current on the following graph.