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Two ac sources feed a common variable resistive load as shown in the given figure. Under maximum power transfer condition, power absorbed by the load resistance RL is _______ W
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- 150
- 75
- 125
- 625
Correct Option: D
For maximum power absorbed by RL
RL = √RTH² + XTH²
= √3² + 4² = 5
Now, 110 = (6 + j8 + 5) I 1 + 5I 2 ...(i)
and 90 (6 + j8 + 5) I 2 + 5I 1 ...(ii)
Solving equation (i) and (ii), we get
I 1 = 5.5 – 2.75 j
I 2 = 4.5 – 2.2 j
∴ Total current in RL = I 1 + I 2
= (10 – 4.55 j) A = 11.15 A
Power absorbed by RL = I2 R
= (11.15)2 × 5 = 625 W.
