Question
What is the effect on the magnitude of pure reactance when it is converted to susceptance?
Answer Options
- A) It is unchanged
- B) The sign is reversed
- C) It is shifted by 90 degrees
- D) It is replaced by its reciprocal
Correct Answer: D
Explanation
Reactance (X) is the imaginary part of impedance (Z). Susceptance (B) is the imaginary part of admittance (Y). Admittance is the reciprocal of impedance (Y = 1/Z), and susceptance is the reciprocal of reactance (B = 1/X) for a purely reactive circuit. The relationship is a mathematical inversion.
Therefore, when pure reactance (X) is converted to susceptance (B), the magnitude of the value is replaced by its reciprocal. For instance, a pure reactance of 50 \Omega converts to a susceptance magnitude of 1/50 = 0.02 \text{ Siemens}. Additionally, the sign is also reversed: inductive reactance (+jX) becomes negative susceptance (-jB), and capacitive reactance (-jX) becomes positive susceptance (+jB).
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