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Unit 6 Practice Sheet: Thevenin's, Norton's, Maximum Power Transfer EGR 2201 Reeder 1. Finding the Thevenin-equivalent circuit (no dependent sources). Practice Problem 4.8 from the textbook: a. Redraw this circuit with the 1- load resistor removed. b. Find the circuit’s Thevenin-equivalent voltage VTh by finding the voltage across the two open terminals in your redrawn circuit. c. Redraw your circuit from Step a, this time turning off all independent sources. d. Find the Thevenin-equivalent resistance RTh by finding the resistance looking into the two open terminals in your second redrawn circuit. e. Draw the Thevenin-equivalent circuit of the original circuit. EGR 2201 Unit 6 Practice sheet - 2 2. Finding the Thevenin-equivalent circuit (with dependent sources). Practice Problem 4.9 from the textbook: In the circuit shown below, the load has already been removed, leaving us with two open terminals labeled a and b. a. Find the Thevenin-equivalent voltage VTh by finding the voltage across the two open terminals. b. Redraw the circuit, turning off all independent sources. c. Modify your redrawn circuit by connecting an independent voltage source of any value (let’s say, vo = 1 V) across terminals a and b. d. In your redrawn circuit, find the current io that flows into terminal a. e. To find the Thevenin-equivalent resistance RTh divide the voltage from Step c by the current from Step d. In symbols, RTh = vo ÷ io. f. Draw the Thevenin-equivalent circuit of the original circuit. EGR 2201 Unit 6 Practice sheet - 3 3. Finding the Norton-equivalent circuit (no dependent sources). Example 4.11 from the textbook: a. Find the circuit’s Thevenin-equivalent voltage VTh. b. Redraw the circuit, turning off all independent sources. c. Find the circuit’s Thevenin-equivalent resistance RTh. d. Using your results from Steps a and c, find the Norton-equivalent current IN and the Norton-equivalent resistance RN. e. Draw the Norton-equivalent circuit of the original circuit. EGR 2201 Unit 6 Practice sheet - 4 4. Maximum Power Transfer. Practice Problem 4.13 from the textbook: a. Find the Thevenin-equivalent voltage VTh of the circuit to the left of terminals a and b, with the load resistor removed. b. Redraw the circuit (without the load resistor), turning off all independent sources. c. Modify your redrawn circuit by connecting an independent voltage source of any value (let’s say, vo = 1 V) across the open terminals a and b. d. In your redrawn circuit, find the current io that flows into terminal a. e. Find the Thevenin-equivalent resistance RTh , recalling that RTh = vo ÷ io. f. Draw the Thevenin-equivalent circuit of the original circuit. g. What value of RL will draw maximum power from the rest of the circuit? Calculate the maximum power. EGR 2201 Unit 6 Practice sheet - 5 5. Source Modeling. The following circuit shows a variable load resistor connected across a real voltage source, which is modeled as an ideal source in series with an internal resistance. a. Find the voltage across the load resistor if RL = 1 k. (Hint: use the voltage-divider rule.) b. Find the voltage across the load resistor if RL = 100 . c. Find the voltage across the load resistor if RL = 10 . d. Find the voltage across the load resistor if RL = 5 .