*Question E5B05:
What is the effect on the magnitude of pure reactance when it is converted to susceptance?*  

*Correct Answer is  D: It is replaced by its reciprocal*  

### AI Response: (may contain errors)  

When dealing with reactance and susceptance, it's important to understand their relationship in the context of AC circuits.

### Explanation:

1. **Correct Answer: It is replaced by its reciprocal (D)**

   - **Reactance ($X$)** is a measure of how much a component resists the change in current due to its inductance or capacitance. It is measured in ohms ($\Omega$).
   - **Susceptance ($B$)** is the reciprocal of reactance and is a measure of how easily a circuit allows the flow of AC current. It is measured in siemens (S).
   - The relationship between reactance and susceptance is given by:
     $$ B = \frac{1}{X} $$
   - Therefore, when reactance is converted to susceptance, its magnitude becomes the reciprocal of the original reactance.

2. **Why the other choices are incorrect:**

   - **Choice A: It is unchanged**  
     This is incorrect because converting reactance to susceptance involves taking the reciprocal, which changes the magnitude.

   - **Choice B: The sign is reversed**  
     This is incorrect because the conversion involves taking the reciprocal, not changing the sign. The sign of susceptance depends on whether the reactance is inductive or capacitive, but the conversion itself does not involve a sign change.

   - **Choice C: It is shifted by 90 degrees**  
     This is incorrect because a phase shift is not involved in the conversion from reactance to susceptance. The conversion is purely a mathematical operation of taking the reciprocal.

### Key Formula:

- To convert reactance to susceptance:
  $$ B = \frac{1}{X} $$

Understanding this relationship is crucial for analyzing AC circuits, especially when dealing with impedance and admittance.