Superposition Theorem

Solved Problems on Superposition Theorem

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1) Find Current flowing through 1 \Omega resistor by using superposition theorem.

Superposition Theorem solved examples
Superposition Theorem solved problems

Consider 130 V Voltage source only.

-0.2I_1-0.2(I_1-I_2)+130 = 0 

-0.4I_1 +0.2I_2 = -130 \ldots\ldots (1)

-I_1-0.2(I_2-I_1)-0.2I_2=0

0.2I_1-1.4I_2=0 \ldots\ldots (2) 

I_1 = 350 A

I_2 = 50 A

I’_{1\Omega} = 50 A (\downarrow)

Superposition Theorem solved Numerical

Consider 110 V only.

-0.2I_1 -0.2(I_1-I_2)-110 = 0

-0.4I_1+0.2I_2 = 110 \ldots\ldots(3)

-I_2+110-0.2(I_2-I_1)-0.2I_2=0

0.2I_1 – 1.4I_2 = -110 \ldots\ldots (4)

I_1 = -253.8467 A

I_2 = 42.3076 A

I’’_{1\Omega} = 42.3076 A (\downarrow)

\therefore I_{1\Omega} = I’_{1\Omega} + I’’_{1\Omega} = 50 + 42.3076 = 92.3076 A (\downarrow)

2) Find current flowing through 5 \Omega .

Superposition Theorem
Superposition Theorem

2-0.1I_1-10I_1-5(I_1-I_2)=0

15.1I_1 + 5I_2=-2 \ldots\ldots (1)

-20I_1-0.2I_2-5(I_2-I_1)=0

5I_1-25.2I_2=0 \ldots\ldots (2)

I_1 = 0.1417 A

I_2 = 0.02812 A

I’_{5\Omega} = I_1-I_2 = 0.1158 A (\downarrow)

Superposition Theorem

Consider 4 V only.

-0.1I_1-10I_1-5(I_1-I_2) = 0

-15.1I_1+5I_2 = 0 \ldots\ldots (3)

20I_2-0.2I_2-4-5(I_2-I_1)=0

5I_1-25.2I_2 = 4 \ldots\ldots (4)

I_1 = -0.05685 A
I_2 = -0.1698 A

I’’_{5 \Omega} = I_2-I_1 = 0.1130 A (\downarrow)

I_{5 \Omega} =  I’_{5\Omega} +  I’’_{5\Omega} = 0.2288 A (\downarrow)

3) Determine current through 1 \Omega resistor.

Superposition Theorem solved problems
Superposition Theorem solved problems

Consider a 10 V voltage source only.

-2(I_1-I_2)-2I_1 = 0

-4I_1+2I_2=0 \ldots\ldots (1)

-10 -2(I_2-I_1)-I_2=0

2I_1-3I_2=10 \ldots\ldots (2)

I_1 = -2.5 A

I_2 =-5 A

I’_{1\Omega} = -5 A (\rightarrow)

Superposition Theorem solved problems

Consider a 6 V voltage source only.

-2I_1-2(I_1-I_2)-6 = 0

-4I_1+2I_2=6 \ldots\ldots (3)

-I_2+6-2(I_2-I_1)=0

2I_1 – 3I_2 =-6 \ldots\ldots (4)

I_1 = -0.75 A

I_2 =1.5 A

I’’_{1\Omega} = 1.5 A (\rightarrow)

Superposition Theorem solved problems

Consider 8 V only.

8-2I_1-2(I_1-I_2)=0

-4I_1+2I_2=-8 \ldots\ldots (5)

-I_2-2(I_2-I_1)=0

2I_1-3I_2=0 \ldots\ldots (6)

I_1 = 3 A

I_2 = 2 A

I’”_{1\Omega} = 2 A (\rightarrow)

Total \; \; current \; \; I_{1 \Omega}=I’_{1 \Omega}+I’’_{1 \Omega}+I’’’_{1 \Omega}

I_{1 \Omega}= 2+1.5+(-5) = -1.5 A (\rightarrow)

I_{1 \Omega} = 1.5 A (\leftarrow)

4) Find current through 20 \Omega resistor.

Superposition Theorem solved problems
Superposition Theorem solved problems

For Mesh 1:

10-10I_1+10I_2=0

-10I_1+10I_2=-10 \ldots \ldots(1)

For Mesh 2:

-10I_2+10I_1-I_2-20I_2=0

10I_1-31I_2=0 \ldots\ldots(2)

I_1 = 1.4761 A

I_2 = 0.4761 A

I’_{20\Omega} = 0.4761 A (\downarrow)

Superposition Theorem solved problems

Consider 8 V voltage source only.

-I-8-20I=0

-21I = 8

I’’_{20\Omega} = -0.3809 A (\downarrow)

Superposition Theorem solved problems

Consider a 12 V voltage source only.

-12-8I_1+8I_2=0

-8I_1+8I_2=12 \ldots\ldots(3)

-I_2-8I_2+8I_1-20I_2=0

8I_1-29I_2=0 \ldots\ldots(4)

I_1=-2.0714 A

I_2=-0.5714 A

I’’’_{20\Omega} = -0.5714 (\downarrow)

I_{20\Omega} = I’_{20\Omega}+I’’_{20\Omega}+I’’’_{20\Omega}

I_{20\Omega} = 0.4761+(-0.3809)+(-0.5714)

I_{20\Omega} = -0.4762 A  (\downarrow)

I_{20\Omega} = 0.4762 A  (\uparrow)

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