Math Problem Statement

Solve

Determine the currents i1, i2, and i3 using mesh current analysis.

Solution

To solve this circuit problem using mesh current analysis, let us break it down systematically. The goal is to find i1i_1, i2i_2, and i3i_3.

Step 1: Define Mesh Currents

  • Let i1i_1, i2i_2, and i3i_3 represent the currents in the three loops as indicated in the diagram.

Step 2: Apply KVL (Kirchhoff's Voltage Law) in Each Loop

Loop 1: i1i_1

244(i1i2)2i1=024 - 4(i_1 - i_2) - 2i_1 = 0 24=6i14i224 = 6i_1 - 4i_2 6i_1 - 4i_2 = 24 \tag{1}

Loop 2: i2i_2

  • The dependent voltage source is 3v03v_0, where v0=4(i3i2)v_0 = 4(i_3 - i_2). Hence: 3v0=3[4(i3i2)]=12(i3i2)3v_0 = 3[4(i_3 - i_2)] = 12(i_3 - i_2)

Writing KVL for Loop 2: 4(i2i1)+2i212(i3i2)=0-4(i_2 - i_1) + 2i_2 - 12(i_3 - i_2) = 0 Simplify: 4i2+4i1+2i212i3+12i2=0-4i_2 + 4i_1 + 2i_2 - 12i_3 + 12i_2 = 0 4i114i212i3=04i_1 - 14i_2 - 12i_3 = 0 4i_1 - 14i_2 + 12i_3 = 0 \tag{2}

Loop 3: i3i_3

12(i3i2)+8i3+4i3=012(i_3 - i_2) + 8i_3 + 4i_3 = 0 12i312i2+8i3+4i3=012i_3 - 12i_2 + 8i_3 + 4i_3 = 0 24i312i2=024i_3 - 12i_2 = 0 12i2=24i312i_2 = 24i_3 i_2 = 2i_3 \tag{3}


Step 3: Solve the System of Equations

We now have the following three equations:

  1. 6i14i2=246i_1 - 4i_2 = 24
  2. 4i114i2+12i3=04i_1 - 14i_2 + 12i_3 = 0
  3. i2=2i3i_2 = 2i_3

Substitute i2=2i3i_2 = 2i_3 into (1) and (2):

From (1): 6i14(2i3)=246i_1 - 4(2i_3) = 24 6i18i3=246i_1 - 8i_3 = 24 6i1=24+8i36i_1 = 24 + 8i_3 i_1 = 4 + \frac{4i_3}{3} \tag{4}

From (2): 4i114(2i3)+12i3=04i_1 - 14(2i_3) + 12i_3 = 0 4i128i3+12i3=04i_1 - 28i_3 + 12i_3 = 0 4i116i3=04i_1 - 16i_3 = 0 i_1 = 4i_3 \tag{5}


Step 4: Solve for i3i_3

Equating (4) and (5): 4+4i33=4i34 + \frac{4i_3}{3} = 4i_3 4=4i34i334 = 4i_3 - \frac{4i_3}{3} 4=12i34i334 = \frac{12i_3 - 4i_3}{3} 4=8i334 = \frac{8i_3}{3} i3=128=1.5Ai_3 = \frac{12}{8} = 1.5 \, \text{A}


Step 5: Find i1i_1 and i2i_2

From (5): i1=4i3=4(1.5)=6Ai_1 = 4i_3 = 4(1.5) = 6 \, \text{A}

From (3): i2=2i3=2(1.5)=3Ai_2 = 2i_3 = 2(1.5) = 3 \, \text{A}


Final Answer:

  • i1=6Ai_1 = 6 \, \text{A}
  • i2=3Ai_2 = 3 \, \text{A}
  • i3=1.5Ai_3 = 1.5 \, \text{A}

Would you like a more detailed step-by-step explanation or have any specific questions?


Follow-Up Questions:

  1. What is the principle behind mesh current analysis?
  2. How does the presence of a dependent source affect KVL equations?
  3. Why do we substitute i2=2i3i_2 = 2i_3 to simplify the equations?
  4. Can you solve this circuit using nodal analysis instead of mesh analysis?
  5. How do you interpret the direction of the mesh currents physically?

Tip:

Always double-check dependent sources and their controlling variables when writing KVL equations, as errors there can propagate through your solution.

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Math Problem Analysis

Mathematical Concepts

Mesh Current Analysis
Kirchhoff's Voltage Law (KVL)
Dependent Sources

Formulas

KVL: ΣVoltages in a closed loop = 0
Dependent source relationship: Voltage or current depends on a circuit parameter
System of linear equations for solving mesh currents

Theorems

Kirchhoff's Voltage Law

Suitable Grade Level

Undergraduate Engineering (Electrical/Electronics)