## ELEC153 Circuit Theory II M2A4 Lab: AC Parallel Circuits Introduction In this experiment we work with AC parallel circuits. As we did in the AC series circuits lab, the results obtained through Transient Analysis in MultiSim will be verified by manual calculations. Procedure 1. Figure 1 is the circuit we want to analyze.The voltage source is 24 volts peak at 1000 Hz. Figure 1: AC parallel circuit used for analysis using MultiSim Unlike the series circuit, there is no resistor in series with the voltage source that allows us to plot the current by taking advantage of its in-phase relationship. So, in order to measure the current produced by the source (total current) add a 1 Ohm resistor in series with the source. This small resistor will not affect the calculations. Figure 2: Arrangement for analyzing the current waveforms 2. Run the simulations and with the oscilloscope measure both the source voltage and the voltage across the resistor. You should get a plot similar to the following graph: Figure 3: Source voltage (red) and source current (blue) waveforms 3. From the resulting analysis plot, determine the peak current. Record it here. Measured Peak Current 4. Determine the peak current by calculation. Record it here. Does it match the measured peak current? Explain. Calculated Peak Current 5. Calculate the phase-shift. Using the method presented in the last lab, measure the time difference at the zero-crossing of the two signals. Record it here. Time difference 6. From the resulting calculation, determine the phase shift by using the following formula Record it here. Measured Phase Shift 7. Determine the phase shift by calculation. Record it here. Does it match the measured phase shift? Explain. Calculated Phase Shift 8. Change the frequency of the voltage source to 5000 Hz. Re-simulate and perform a Transient Analysis to find the new circuit current and phase angle. Measure them and record them here: Measured Current Measured Phase Shift 9. Perform the manual calculations needed to find the circuit current and phase shift. Record the calculated values here. Do they match the measured values within reason? What has happened to the circuit with an increase in frequency? Calculated Current Calculated Phase Shift 10. Replace the capacitor with a 0.8 H inductor. Set the source frequency back to 1000 Hz. Perform Transient Analysis and measure the current amplitude and phase shift. Record them here: Measured Current Measured Phase Shift 11. Perform the manual calculations needed to find the circuit current and phase shift. Record the calculated values here. Do they match the measured values within reason? Calculated Current Calculated Phase Shift 12. Change the frequency of the voltage source to 5000 Hz. Re-simulate and perform a Transient Analysis to find the new circuit current and phase angle. Measure them and record them here: Measured Current Measured Phase Shift 13. Perform the manual calculations needed to find the circuit current and phase shift. Record the calculated values here. Do they match the measured values within reason? What has happened to the circuit with an increase in frequency? Calculated Current Calculated Phase Shift Write-up and Submission In general, for each lab you do, you will be asked to setup certain circuits, simulate them, record the results, verify the results are correct by hand, and then discuss the solution. Your lab write-up should contain a one page, single spaced discussion of the lab experiment, what went right for you, what you had difficulty with, what you learned from the experiment, how it applies to our coursework, and any other comment you can think of. In addition, you should include screen shots from the MultiSim software and any other figure, table, or diagram as necessary.

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