*Question E5A06:
What is the magnitude of the circulating current within the components of a parallel LC circuit at resonance?*  

*Correct Answer is  B: It is at a maximum*  

### AI Response: (may contain errors)  

In a parallel LC circuit at resonance, the inductive reactance ($X_L$) and capacitive reactance ($X_C$) are equal in magnitude but opposite in phase, effectively canceling each other out. This results in the circuit having a purely resistive impedance, which is at its maximum. However, the circulating current within the LC components is at its maximum.

### Explanation:

1. **Correct Answer (B: It is at a maximum):**
   - At resonance, the impedance of the LC circuit is at its maximum, but the circulating current between the inductor and capacitor is at its maximum. This is because the energy is continuously exchanged between the inductor and capacitor, leading to high currents within the LC loop, even though the overall current from the source is minimized.

2. **Why Other Choices Are Incorrect:**
   - **Choice A (It is at a minimum):** This is incorrect because, at resonance, the circulating current is not minimized; it is maximized due to the energy exchange between the inductor and capacitor.
   - **Choice C (It equals 1 divided by the quantity 2 times pi, times the square root of (inductance L multiplied by capacitance C)):** This describes the formula for the resonant frequency, not the circulating current. The resonant frequency $f_0$ is given by:
     $$ f_0 = \frac{1}{2\pi\sqrt{LC}} $$
   - **Choice D (It equals 2 times pi, times the square root of (inductance L multiplied by capacitance C)):** This is incorrect as it does not relate to the circulating current or any standard formula for resonance in an LC circuit.

### Useful Formula:

- **Resonant Frequency:**
  $$ f_0 = \frac{1}{2\pi\sqrt{LC}} $$

At resonance, the energy oscillates between the inductor and capacitor, leading to maximum circulating current within the LC components, even though the impedance seen by the source is at its maximum.