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

Choices:  
A: G  
B: X  
C: Y  
D: B    

Correct Answer is  D: B  

Susceptance is the imaginary part of admittance, and it is denoted by the letter $B$.  
Among the choices, that corresponds to choice D: B.

Why the correct answer is correct:
- In admittance form, $$Y = G + jB,$$ where:
  - $G$ is conductance (real part),
  - $B$ is susceptance (imaginary part).
- Therefore, the commonly used symbol for susceptance is $B$.

Why the other choices are incorrect:
- A: G — This is conductance, the real part of admittance.
- B: X — This is reactance, the imaginary part of impedance.
- C: Y — This is admittance itself (the total), not specifically susceptance.

Useful formulas and associations:
- Impedance: $$Z = R + jX$$
- Admittance (inverse of impedance): $$Y = \frac{1}{Z} = G + jB$$
- Element susceptances:
  - Capacitor: $$B_C = \omega C$$
  - Inductor: $$B_L = -\frac{1}{\omega L}$$
- Units: $G$ and $B$ are in siemens (S); $R$ and $X$ are in ohms (Ω).