Circuit Analysis – Week #3 Lab Capacitors and Inductors

This Lab has two parts. Please complete both.

Part 1: Build the following circuit in Multisim. Use a square wave and 10 Vp in the function generator.

Calculate the L/R time constant (The ratio of inductance in henry with the resistance in ohms is the time constant in seconds). What is the time constant (L/R)? • Use transient analysis to observe both the input and output of the RL voltage divider. Make a printout of the output. Initially the voltage across the inductor jumps to 20 V, there after the voltage decays exponentially to 0. • Use the cursors to find the amount of time it takes to decay to 36.8% (1/e) of the original (20V) voltage. What is the measured time constant? Show simulation and measurements. • This time should equal the time constant of the circuit (L/R), is it? Sometimes we use 1/3 as an approximation to 1/e. • How accurate is this approximation in percent? Show calculated versus measured accuracy.
Part 2: An inductor has a small amount of capacitance in parallel to the inductance. To illustrate the effect that this has, build the following circuit.

Run this circuit using the transient analysis (run the analysis for about 1 μ Sec). Now remove the capacitor and again run the analysis.

Plot both runs and then describe the difference between runs. • This is one reason that inductors are used much less frequently than capacitors and resistors. What is the difference?
Rules for lab submissions: 1. The lab document must be a Word document. PDF files are NOT accepted. 2. All screenshots must be included. 3. All Multisim screenshots must include the date/time stamp. See TOOLS AND TEMPLATES for the procedure to display the date and time. 4. Any and all Multisim files must be submitted. 5. Any equations used must be typed in Word. Copy and paste of equations from outside sources is prohibited. 6. No graphics are allowed in the Word document other than screenshots of circuits from Multisim and hardware if applicable, with the date/time stamp. 7. The lab template should be used. Specifically, it is brought to your attention that a summary MUST be provided explaining the results of the labs, the relationship of the results to expected results, and any challenges encountered. 8. Hardware portion of labs should include screenshots of the assembled circuit with your name and student GID number written on paper next to the circuit. There should be screenshots of the instrument readings with the date and time stamp on lower right corner clearly shown. See example below.

Any violation of the submission rules above will result in a grade of 1.

Lab 3 Grading Rubric

Demonstrate understanding of Capacitors and their functionality 10 points

Calculated results 10 points

Circuit design in Multisim 10 points

Measurement of time constant and decay of circuit 1 20 points

Transient analysis of circuit 2 20 points

Removal of capacitor and simulation 10 points

Analysis of results 10 points

Lab Report (includes table, measurement with proper units, screenshots, APA guidelines)