Objective: The objectives of this lab are to: (a) Analyze the RC series circuit characteristics. (b) Compare the measure

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Objective The Objectives Of This Lab Are To A Analyze The Rc Series Circuit Characteristics B Compare The Measure 1 (71.15 KiB) Viewed 29 times

Objective: The objectives of this lab are to: (a) Analyze the RC series circuit characteristics. (b) Compare the measured and computed values for voltages and phase angles. (c) Draw a phasor diagram for voltages. Theory: As you have studied during lecture, the capacitor is represented in an AC circuit by -JXc. The reactance, which is Xc = 1/(2nfc), decreases as the frequency increases. Thus, the faster the source oscillation, the less opposition to the change in voltage. With less impedance, the output voltage across the capacitor decreases, as frequency increases. Materials needed: > One 270 ohm Resistor > One 1μF Capacitor Function Generator Circuit to be built for analysis: n R1 270 Ohm www 1v@ 1kHz 1uF 1. Using circuit 3-1, calculate the total current (which is also the capacitor current and resistor current) by using Ohm's Law. To do this, you must first compute the total impedance of the circuit, in polar form. Also, remember that. 's (source voltage) phase shift is 0 degrees. Write your answer in polar form. IT = 2. Compute the voltage across the capacitor (C1), using Ohm's Law and your result from #1. Write your answer polar form. Vc = 3. In a series RC circuit, the voltage across the capacitor lags the total current by 90° Using your answer for #1 and #2, verify that this is true. What is the phase difference between your calculated values for IT and Vc? Phase difference between Ir and Vc:. 4. Compute the voltage across the resistor (R1), using Ohm's Law. Write your answer in polar form. VR = 5. In a series RC circuit, the voltage across the resistor is in phase with the current flowing through it. Using your answer for #1 and #2, verify that this is true. Are VR and IT in phase with each other?

6. Build circuit 3-1, using all necessary parts your AC lab kit. Supply a 1 V (peak) sine wave at 1kHZ from the function generator. 7. On the oscilloscope, connect channel 1 to the node where the resistor and the function generator meet, and channel 2 to the node where the capacitor and resistor meet. Verify the peak voltage from the function generator is approximately 1.0 V. Voltage peak from function generator = 8. Verify the voltage across the capacitor (Vc) by measuring the voltage peak across C1, and the phase between Vs and Vc, on the scope. (You can measure phase difference by selecting "Measure" -> "Time", then select the second "Phase 1-2" option.) Complete Table 3-1. Calculated Value Measured Value Voltage Peak Across C1 Phase difference between V, and C₁ Table 3-1: Comparison of Measured and Calculated Values for Vc 9. A second way to measure phase is to complete the following steps: a. Measure the time delay to between the V, and V, and, and the period of the source voltage. (Use "Measure", "Time" to find the time delay options, choose the 2nd one). td = T = (T = period of Vs) b. Using these values, compute the phase angle between these two voltages, where the phase angle equals: 0 (360°) to/T 0 = 10. Compare the values obtained in steps 8 and 9 for the phase difference of V.. Are the similar? 11. Verify the voltage across the resistor (VR) by measuring VR, using the oscilloscope. C. To measure VR, press the "MATH" button on the oscilloscope. d. Under the "Operate" menu, Select "A-B" e. Select CH1 for Source A, and CH2 for Source B. f. Use a cursor to measure the peak value of the waveform (in purple) that represents VR = V₁-Vc = Channel 1 - Channel 2. Your value will be a close approximation of VR. You will not calculate phase for this step.. Instructor's Initial Calculated Value Measured Value Table 3-2: Comparison of Measured and Calculated Values for VR Voltage Peak Across R1 12. Change the source frequency to the values shown in table 3-2. Measure the voltage across the capacitor C1. What happens to the voltages as you increased the frequency? Explain. Voltage (Vpeak) across C1 5 KHz 10 KHz Table 3-2: RC series results 13. In this experiment, you were given a series RC circuit (Figure 3-1). You first calculated the total current in the circuit (IT), the voltage across the resistor (VR), and the voltage across the capacitor (Vc). Then, after building the circuit on the breadboard, you took measurements to verify the values of VR and Vc. To conclude this experiment, draw a phasor diagram for the voltages in this circuit. Include VR, Vs, and Vc. Use your measured values from the experiment. Clearly label each phasor; make sure that magnitude and direction are shown. End c