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In a two-branch parallel AC circuit, branch A has resistance R_A = 20 ohm and inductive reactance X_L = 15 ohm; branch B has resistance R_B = 6 ohm and capacitive reactance X_C = 8 ohm. The total current supplied by the source is I = sqrt(29) A. Find the current in branch A.

1. Zero
2. 4A
3. 2 A
4. 5 A

Correct answer: 2 A

Solution

The parallel equivalent impedance magnitude is 250/sqrt(725), giving V = sqrt(29)*250/sqrt(725) = 50 V. Current in branch A = V/Z_A = 50/25 = 2 A.

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