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It x is the system reactance and r is its resistance, the power transferred is maximum when
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- x = r
- x = √2r
- x = √3r
- x = 2r
Correct Option: C

| I = | ||
| Z∠θ |
| = | ∠(δ - ∠0) - | ∠- θ | ||
| Z | Z |
Power received, P2 = Re [V2I*]
| = Re | ![]() | V2 | ![]() | ∠(θ - δ) - | ∠θ | ![]() | ![]() | ||
| Z | Z |
| = | cos(θ - δ) - | cos θ | ||
| Z | Z |
Let θ = 90° – α, then
| = | cos(90° - α - δ) - | cos(90° - α) | ||
| Z | Z |
| = | sin(α + δ) - | sin α | ||
| Z | Z |
| P2 max = | - | sin α[α + δ = 90°] | ||
| Z | Z |
| As, sin α = | , then | |
| Z |
| P2 max = | - | . | |||
| √r² + x² | √r² + x² | √r² + x² |
For P2 max to be maximum,
| = 0 | |
| dx |
| or V²2 | ![]() | - | ![]() | = 0 | ||
| (r² + x²)2/3 | (r² + x²)² |
Here V1 = V2
∴ r² + x² = 4r²
or x = √3r



