LAB 3

1

ENGR2105 Lab3 Superposition Theorem

Student Name __________________________________

Objectives:

To solve a network containing resistors and multiple power sources. To learn the use of a

computer to solve electrical circuits and compare calculated results with simulated results.

Materials:

Computer to access Multisim Live. Calculator.

Background Information:

The Superposition Theorem can be used to solve circuits including resistors and multiple

sources. It can be applied only when all the components are linear and passive. The main idea is

that the effect of all power sources can be found by summing the effects of each power source

individually.

You are expected to show all the formulas and calculations needed to find the answers. These

can be handwritten in the worksheets. Take screenshots of each of the Multisim measurements

that you take.

2

ENGR2105 Lab3 Superposition Theorem Worksheet

Apply Superposition Theorem to Circuit 1 to find the current through Resistor 2:

Fig 1. Circuit1

Procedure:

• Build the circuit in Fig1 in MultiSim.

• Measure the voltage potential at point Pcurrent through each resistor (Screen Shot):

Measured I_2 = ________________

• Apply Superposition Theorem to the circuit in Fig 1.

Step1: Short power supply V2

Step2: Calculate the current through R2 for this circuit. This is the contribution to the

current from power supply V1.

Step3: Build this circuit in MultiSim and verify the current through R2. (Screen Shot)

Calculated I_2 = ________ Measured I_2 =________ Direction = ____________

Step4: Reconnect the Power Supply V2 and short power supply V1.

Step 5: Calculate the current through R2 for this circuit. This is the contribution to the

current from power supply V2. Build this circuit in Multisim and measure the

current. (Screen Shot)

Calculated I_2 = ________ Measured I_2 =________ Direction = ____________

Step6: Combine the effects of the two power supplies by adding or subtracting the two

currents (Hint: Are the power supplies pushing positive charge in the same

direction?.

Calculated I_2 = ________________ Direction of I_2 = ________________

Does it match what you found in the first measurement? If not, something is wrong.

3

Apply Superposition Theorem to Circuit 2 to find the current through R3.

Fig 2. Circuit2

Procedure:

• Build the circuit in Fig. 2 in MultiSim. Pay attention to the polarity (orientation) of V2

throughout this problem.

• Use Multisim to measure the current through R3 (Screen Shot):

Measured I_3 = ________________

• Apply Superposition Theorem to the circuit in Fig 2.

Step1: Short power supply V2

Step2: Calculate the current through R3. This is the contribution from power supply V1.

Step3: Build this circuit in Multisim and measure R3 to verify your result. (Screen

Shot)

Calculated I_3 = ________ Measured I_3 =________ Direction = ____________

Step4: Restore V2 and short V1. Pay attention to the polarity (orientation) of V2!

Compute the current through R3. This is the contribution from power supply V2.

Step5: Build the circuit in Fig 2 in MultiSim and measure the current through R3

(Screen Shot).

Calculated I_3 = ________ Measured I_3 =________ Direction = ____________

Step6: Add the effects of the two power supplies by adding OR subtracting the two

currents

Calculated I_3 = ________________ Direction = ____________

Does it match what you found in the first measurement? If not, something went wrong.