*Question E5B02:
What letter is commonly used to represent susceptance?*  

*Correct Answer is  D: B*  

### AI Response: (may contain errors)  

In electrical engineering, particularly in the context of AC circuits, susceptance is a measure of how easily a circuit or component will allow the flow of alternating current. It is the imaginary part of admittance, which is the inverse of impedance.

1. **Correct Answer: D (B)**  
   - The letter "B" is commonly used to represent susceptance. Susceptance is the imaginary part of admittance and is measured in siemens (S). It is used to describe the reactive component of admittance in AC circuits.

2. **Why the Other Choices are Incorrect:**
   - **A: G**  
     - "G" represents conductance, which is the real part of admittance. Conductance measures how easily a circuit allows the flow of direct current (DC) and is also measured in siemens (S).
   - **B: X**  
     - "X" represents reactance, which is the imaginary part of impedance. Reactance measures the opposition to the change in current in an AC circuit and is measured in ohms (Ω).
   - **C: Y**  
     - "Y" represents admittance, which is the inverse of impedance. Admittance is a complex quantity that includes both conductance (real part) and susceptance (imaginary part).

3. **Useful Formulas:**
   - Admittance ($Y$) is the inverse of impedance ($Z$):  
     $$ Y = \frac{1}{Z} $$
   - Admittance can be expressed as a complex number:  
     $$ Y = G + jB $$
     where:
     - $G$ is the conductance (real part),
     - $B$ is the susceptance (imaginary part),
     - $j$ is the imaginary unit.

Understanding these concepts and their representations is crucial for analyzing AC circuits and solving related problems on the FCC exam.