Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 57 of 127
What is the standard SI unit for both capacitive reactance \(X_C\) and inductive reactance \(X_L\)?
A
Ohm (\(\Omega\))
B
Farad (F)
C
Henry (H)
D
Siemens (S)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Ohm (\(\Omega\))
Concept:

Reactance represents the opposition to the flow of alternating current and is defined as the ratio of voltage in volts to current in amperes.

Formula / Reaction:

$$\text{Unit of } X = \frac{\text{Volt}}{\text{Ampere}} = \text{Ohm } (\Omega)$$

Solution:

  • Both \(X_C = \frac{1}{\omega C}\) and \(X_L = \omega L\) have dimensions of electrical resistance: \([\text{M L}^2 \text{T}^{-3} \text{A}^{-2}]\).


  • The SI unit for both reactances is the Ohm (\(\Omega\)).


Why other options are incorrect:

  • Opt_B: Farad is the unit of capacitance \(C\).


  • Opt_C: Henry is the unit of inductance \(L\).


  • Opt_D: Siemens is the unit of conductance and susceptance.

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