Kirchhoff’s Rule Part-3

Q Find the currents in the given circuit

Find Current in Each Branch

🔍 Given Circuit

Let the branch currents be:

  • $I_1$ in the lower branch
  • $I$ in the middle branch
  • $I_3$ in the upper branch

Using Kirchhoff’s Current Law (KCL) at junction F:I1+I2=I3I_1 + I_2 = I_3


🔄 Loop ABCF

Applying Kirchhoff’s Loop Rule (KVL):(I1+I2)(1)22I21=0-(I_1+I_2)(1)-2-2I_2-1=0Expanding:I1I222I21=0-I_1-I_2-2-2I_2-1=0 I13I23=0-I_1-3I_2-3=0

Therefore,I1+3I2=3I_1+3I_2=-3

Equation (1)


🔄 Loop ABDE

Applying KVL:(I1+I2)(1)2+42I1=0-(I_1+I_2)(1)-2+4-2I_1=0

Expanding:I1I22+42I1=0-I_1-I_2-2+4-2I_1=03I1I2+2=0-3I_1-I_2+2=0

Therefore,3I1+I2=23I_1+I_2=2

Equation (2)


✏️ Solving Equations (1) and (2)

From Equation (1):I1+3I2=3I_1+3I_2=-3

Multiply by 3:3I1+9I2=93I_1+9I_2=-9

Equation (2):3I1+I2=23I_1+I_2=2

Subtracting:8I2=118I_2=-11I2=118AI_2=-\frac{11}{8}A

Current in middle branchI2=118A\boxed{I_2=-\frac{11}{8}A}


Substituting into Equation (2):3I1118=23I_1-\frac{11}{8}=2 3I1=2783I_1=\frac{27}{8}I1=98AI_1=\frac{9}{8}A

Current in lower branchI1=98A\boxed{I_1=\frac{9}{8}A}


🔌 Finding I3I_3

Using KCL:I3=I1+I2I_3=I_1+I_2I3=98118I_3=\frac{9}{8}-\frac{11}{8}I3=28I_3=-\frac{2}{8} I3=14AI_3=-\frac{1}{4}A

Current in upper branchI3=14A\boxed{I_3=-\frac{1}{4}A}


🎯 Final Currents

✅ Upper Branch:I3=14A\boxed{I_3=-\frac{1}{4}A}

✅ Middle Branch:I2=118A\boxed{I_2=-\frac{11}{8}A}

✅ Lower Branch:I1=98A\boxed{I_1=\frac{9}{8}A}


Find Potential Difference Between A and D

Using the upper branch:VA(14×1)2=VDV_A-\left(-\frac{1}{4}\times1\right)-2=V_D VA+142=VDV_A+\frac{1}{4}-2=V_DVA74=VDV_A-\frac{7}{4}=V_D

Therefore,VDVA=74VV_D-V_A=-\frac{7}{4}V

Potential difference between D and AVDVA=74V\boxed{V_D-V_A=-\frac{7}{4}V}

orVAVD=74V\boxed{V_A-V_D=\frac{7}{4}V}

🎉 Hence, the currents in all branches and the potential difference between A and D have been determined.

Comments

Leave a Reply

Your email address will not be published. Required fields are marked *