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Department of Electrical and Electronic Engineering
United International University (UIU)
EEE 104: Electrical Circuits Laboratory
EXPT. NO. 2
Verification of Superposition Principle.
OBJECTIVES
a. To verify superposition principle, which is an analytical technique of determining
currents in a circuit with more than one EMF source.
b. To get familiarized with breadboard implementation
c. To get familiarized with oscilloscope connection and application
THEOREM
In a linear circuit containing multiple independent sources and linear elements (e.g.
resistors, inductors, capacitors) the voltage across (or the current through) any element
when all the sources are acting simultaneously may be obtained by adding algebraically
all the individual voltages (or the currents) caused by each independent source acting
alone, with all other sources deactivated.
APPARATUS
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Two independent dc power supplies
Three rheostats,
One 1 k potentiometer, two 1 k resistors (Breadboard Implementation)
One dc ammeter (0 - 1 A),
One multimeter (used as dc voltmeter, ohmmeter)
Two SPDT switches and one SPST switch
Breadboard
Oscilloscope
Chords and wires
Lab Sheet 2 of EEE 104. Last updated: Summer 2011
Page 1 of 3
PART A: Implementation using Rheostats
PROCEDURES
1) Using three rheostats to set up the circuit as in Fig. 1.
2) You can mark the rheostat and prerecorded values of the resistances for 3
observations.
1 S1
2
S2 1
R2
R1
S3
E1
2
A
E2
R3
I
Fig. 2.1. Circuit diagram for experimenting superposition theorem
3) Connect a dc ammeter in series with R3 resistor.
4) Set the rheostats R1, R2 and R3 at any value above 20.
5) Keep both sources active by keeping S1 and S2 in the proper position (position 1).
6) Apply 25 volts from E1 and 20 volts from E2.
7) Measure the current, I through the resistor R3 and record it in Table 1 for each
observation.
8) Render E2 inactive (keeping E1 active) and measure the current I / in the branch R3
9) Render E1 inactive (keeping E2 active) and measure the current I// in the branch R3
9) Verify if I= I/ + I// which would validate the superposition theorem for this particular
circuit.
10) Vary R3 and repeat steps 4 to 9 for 3 observations of R3.
Lab Sheet 2 of EEE 104. Last updated: Summer 2011
Page 2 of 3
TABLE 1
No.
of
Obs.
1.
2.
3.
R1 R2
( ) ( )
R3
( )
I / (with only
I (with both E1
and E2 active)
E1 active)
(A )
I// (with only
E2 active)
(A)
(A)
IExp =
I/ + I//
Error,
I-IExp
Experimental
PART- B: Implementing Circuit on Breadboard
1. Implement the circuit in Fig. 1 on breadboard. Connect a 1k potentiometer at
R3. Connect 1 k resistors in places of R1 and R2.
2. Instead of switches, use two floating wires. Their floating edges can be manually
connected to 1 or 2 nodes (to make/break a connection) as shown in Fig. 1.
3. Connect the multimeter in series with R3 as a dc ammeter.
4. Apply 10 V dc supply for both sides of Fig. 1 (E1 and E2). Repeat the procedures
in PART A (steps 4 to 9).
5. Connect channel 1 of the oscilloscope with load R3. The oscilloscope will show
the constant dc voltage across R3. Divide this voltage by R3 to obtain the current
values I, I/ , I// for Table 2. Compare the current in shown in multimeter with that
measured from oscilloscope.
6. Change the potentiometer, R3, repeat steps 2-4 and observe the changes in
oscilloscope.
7. Varying R3, take data for three observations in Table 2
TABLE 2
No.
of
Obs.
1.
2.
3.
V from
I (with both E1
Oscilloscope
and E2 active) =
V/R3 (A)
I / (with only I// (with only
E1 active) (A) E2 active) (A)
IExp =
I/ + I//
Error,
I-IExp
Experimental
REPORT:
1. Show results in tabular form.
2. Comment on the obtained results and discrepancies (if any).
Lab Sheet 2 of EEE 104. Last updated: Summer 2011
Page 3 of 3

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