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The equivalent capacitance of three capa...

The equivalent capacitance of three capacitors of capacitance `C_(1):C_(2)` and `C_(3)` are connected in parallel is `12` units and product `C_(1).C_(2).C_(3) = 48`. When the capacitors `C_(1)` and `C_(2)` are connected in parallel, the equivalent capacitance is `6` units. then the capacitance are

A

`2, 3, 7`

B

`1.5, 2.5, 8`

C

`1, 5, 6`

D

`4, 2, 6`

Text Solution

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To solve the problem, we will follow a systematic approach using the given information about the capacitors. ### Step 1: Set up the equations based on the problem statement We are given three capacitors with capacitances \( C_1, C_2, \) and \( C_3 \). The following equations can be derived from the problem: 1. The total capacitance when all three capacitors are connected in parallel: \[ C_1 + C_2 + C_3 = 12 \quad \text{(Equation 1)} \] 2. The product of the capacitances: \[ C_1 \cdot C_2 \cdot C_3 = 48 \quad \text{(Equation 2)} \] 3. The total capacitance when \( C_1 \) and \( C_2 \) are connected in parallel: \[ C_1 + C_2 = 6 \quad \text{(Equation 3)} \] ### Step 2: Express \( C_3 \) in terms of \( C_1 \) and \( C_2 \) From Equation 3, we can express \( C_3 \): \[ C_3 = 12 - (C_1 + C_2) = 12 - 6 = 6 \quad \text{(Equation 4)} \] ### Step 3: Substitute \( C_3 \) into Equation 2 Now, substituting \( C_3 \) from Equation 4 into Equation 2: \[ C_1 \cdot C_2 \cdot 6 = 48 \] Dividing both sides by 6 gives: \[ C_1 \cdot C_2 = 8 \quad \text{(Equation 5)} \] ### Step 4: Express \( C_1 \) in terms of \( C_2 \) From Equation 5, we can express \( C_1 \): \[ C_1 = \frac{8}{C_2} \quad \text{(Equation 6)} \] ### Step 5: Substitute \( C_1 \) into Equation 3 Substituting Equation 6 into Equation 3: \[ \frac{8}{C_2} + C_2 = 6 \] Multiplying through by \( C_2 \) to eliminate the fraction: \[ 8 + C_2^2 = 6C_2 \] Rearranging gives us a quadratic equation: \[ C_2^2 - 6C_2 + 8 = 0 \quad \text{(Equation 7)} \] ### Step 6: Solve the quadratic equation We can solve Equation 7 using the quadratic formula: \[ C_2 = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] Here, \( a = 1, b = -6, c = 8 \): \[ C_2 = \frac{6 \pm \sqrt{(-6)^2 - 4 \cdot 1 \cdot 8}}{2 \cdot 1} \] \[ C_2 = \frac{6 \pm \sqrt{36 - 32}}{2} \] \[ C_2 = \frac{6 \pm \sqrt{4}}{2} \] \[ C_2 = \frac{6 \pm 2}{2} \] This gives us two solutions: \[ C_2 = \frac{8}{2} = 4 \quad \text{or} \quad C_2 = \frac{4}{2} = 2 \] ### Step 7: Find corresponding values of \( C_1 \) Using Equation 6 to find \( C_1 \): 1. If \( C_2 = 4 \): \[ C_1 = \frac{8}{4} = 2 \] 2. If \( C_2 = 2 \): \[ C_1 = \frac{8}{2} = 4 \] ### Step 8: Find \( C_3 \) From Equation 4, we already found: \[ C_3 = 6 \] ### Final Result Thus, the capacitances are: - \( C_1 = 2, C_2 = 4, C_3 = 6 \) or - \( C_1 = 4, C_2 = 2, C_3 = 6 \) ### Summary The capacitances are \( C_1 = 2 \) units, \( C_2 = 4 \) units, and \( C_3 = 6 \) units. ---
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