Question
What does the impedance 50-j25 ohms represent?
Answer Options
- A) 50 ohms resistance in series with 25 ohms inductive reactance
- B) 50 ohms resistance in series with 25 ohms capacitive reactance
- C) 25 ohms resistance in series with 50 ohms inductive reactance
- D) 25 ohms resistance in series with 50 ohms capacitive reactance
Correct Answer: B
Explanation
Impedance expressed in rectangular notation follows the format Z = R + jX, where the first term is the resistive component (R) and the second term (jX) is the reactive component. A positive sign before the j indicates inductive reactance, and a negative sign (-j) indicates capacitive reactance.
Therefore, the impedance \mathbf{50 - j25} ohms represents \mathbf{50 \text{ ohms resistance in series with 25 \text{ ohms capacitive reactance}}. This is the typical impedance format used to characterize a slightly mismatched antenna or a resonant circuit operating below its resonant frequency (where X_C > X_L).
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