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I want the step by step method to solve this question using Kirchoff voltage and current law then solving it simultaneously to get I1 and I2

Physics

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Step-by-step solution

4 steps

To solve this circuit problem, we will use Kirchhoff's Voltage Law (KVL) to set up a system of equations for mesh currents, then solve for these currents. Finally, we will relate them to I1I_1 and I2I_2 and calculate the potential difference across AB.

  1. Define mesh currents and apply KVL.

    Let's define two clockwise mesh currents:

    • i1i_1: Current in the left loop (containing the top 6V source, 2Ω resistor, 3Ω resistor, and middle 6V source).
    • i2i_2: Current in the right loop (containing the middle 6V source, 3Ω resistor, 1Ω resistor, and 6Ω resistor).

    Applying KVL to the left loop (Mesh 1, clockwise):
    Starting from the bottom-left corner and moving clockwise:

    +6V−(i1×2Ω)−((i1−i2)×3Ω)−6V=0+6\text{V} - (i_1 \times 2\Omega) - ((i_1 - i_2) \times 3\Omega) - 6\text{V} = 0 6−2i1−3i1+3i2−6=06 - 2i_1 - 3i_1 + 3i_2 - 6 = 0 −5i1+3i2=0(∗)-5i_1 + 3i_2 = 0 \quad (*)

    Applying KVL to the right loop (Mesh 2, clockwise):
    Starting from the bottom-right corner and moving clockwise:

    +6V+((i1−i2)×3Ω)−(i2×1Ω)−(i2×6Ω)=0+6\text{V} + ((i_1 - i_2) \times 3\Omega) - (i_2 \times 1\Omega) - (i_2 \times 6\Omega) = 0 6+3i1−3i2−i2−6i2=06 + 3i_1 - 3i_2 - i_2 - 6i_2 = 0 3i1−10i2+6=0(∗∗)3i_1 - 10i_2 + 6 = 0 \quad (**)
  2. Solve the system of equations for the mesh currents.

    From equation (∗)(*):

    5i1=3i2  ⟹  i1=35i25i_1 = 3i_2 \implies i_1 = \frac{3}{5}i_2

    Substitute this expression for i1i_1 into equation (∗∗)(**):

    3(35i2)−10i2+6=03\left(\frac{3}{5}i_2\right) - 10i_2 + 6 = 0 95i2−10i2+6=0\frac{9}{5}i_2 - 10i_2 + 6 = 0

    Multiply by 5 to clear the fraction:

    9i2−50i2+30=09i_2 - 50i_2 + 30 = 0 −41i2=−30-41i_2 = -30 i2=3041 Ai_2 = \frac{30}{41} \text{ A}

    Now, substitute i2i_2 back into the expression for i1i_1:

    i1=35×3041=3×641=1841 Ai_1 = \frac{3}{5} \times \frac{30}{41} = \frac{3 \times 6}{41} = \frac{18}{41} \text{ A}
  3. Determine the currents I1I_1 and I2I_2.

    • The current I1I_1 in the diagram flows through the 1Ω resistor. This corresponds to our mesh current i2i_2. I1=i2=3041 AI_1 = i_2 = \frac{30}{41} \text{ A}
    • The current I2I_2 in the diagram flows from B to A through the 3Ω resistor and middle 6V source. In our mesh analysis, i2i_2 flows from B to A, and i1i_1 flows from A to B. Therefore, the net current from B to A is i2−i1i_2 - i_1. I2=i2−i1=3041 A−1841 A=1241 AI_2 = i_2 - i_1 = \frac{30}{41} \text{ A} - \frac{18}{41} \text{ A} = \frac{12}{41} \text{ A}
  4. Determine the potential difference across AB (VABV_{AB}).

    We can find VAB=VA−VBV_{AB} = V_A - V_B by tracing a path from B to A through the middle branch (3Ω resistor and 6V source).
    The current I2I_2 flows from B to A.
    Going from B to A:

    • Voltage drop across the 3Ω resistor: I2×3ΩI_2 \times 3\Omega.
    • Voltage rise across the 6V source (from negative to positive terminal): +6V+6\text{V}.
    VAB=(I2×3Ω)+6VV_{AB} = (I_2 \times 3\Omega) + 6\text{V} VAB=(1241 A×3Ω)+6VV_{AB} = \left(\frac{12}{41} \text{ A} \times 3\Omega\right) + 6\text{V} VAB=3641 V+6 VV_{AB} = \frac{36}{41} \text{ V} + 6\text{ V} VAB=3641 V+6×4141 V=36+24641 V=28241 VV_{AB} = \frac{36}{41} \text{ V} + \frac{6 \times 41}{41} \text{ V} = \frac{36 + 246}{41} \text{ V} = \frac{282}{41} \text{ V}

    The final answers are:

    • i) The current I1I_1 and I2I_2: I1=3041 AI_1 = \boxed{\frac{30}{41} \text{ A}} I2=1241 AI_2 = \boxed{\frac{12}{41} \text{ A}}
    • ii) The p.d. across AB: VAB=28241 VV_{AB} = \boxed{\frac{282}{41} \text{ V}}
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