*Question E5C11:
Which point in Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and an 18-microhenry inductor at 3.505 MHz?*  

*Correct Answer is  B: Point 3*  

### AI Response: (may contain errors)  

To determine the impedance of a series circuit consisting of a resistor and an inductor, we need to calculate the total impedance, which is a combination of resistance and inductive reactance.

### Step-by-step Explanation:

1. **Resistance ($R$):**  
   The resistance is given as 300 ohms.

2. **Inductive Reactance ($X_L$):**  
   The inductive reactance can be calculated using the formula:  
   $$X_L = 2\pi f L$$  
   where:
   - $f$ is the frequency in hertz (Hz)
   - $L$ is the inductance in henries (H)

   For this problem:
   - $f = 3.505 \times 10^6$ Hz (3.505 MHz)
   - $L = 18 \times 10^{-6}$ H (18 microhenries)

   Plugging in the values:  
   $$X_L = 2\pi \times 3.505 \times 10^6 \times 18 \times 10^{-6}$$  
   $$X_L \approx 396.5 \, \text{ohms}$$

3. **Total Impedance ($Z$):**  
   The total impedance of a series circuit is given by:  
   $$Z = R + jX_L$$  
   where $j$ is the imaginary unit.

   So, the impedance is:  
   $$Z = 300 + j396.5 \, \text{ohms}$$

4. **Impedance Representation on a Graph:**
   - The real part (300 ohms) is plotted on the horizontal axis.
   - The imaginary part (396.5 ohms) is plotted on the vertical axis.

   This corresponds to a point in the complex plane with coordinates (300, 396.5).

### Why Point 3 is Correct:
- **Point 3** on Figure E5-1 represents the impedance with a real part of 300 ohms and an imaginary part of approximately 396.5 ohms, which matches our calculated impedance.

### Why Other Choices are Incorrect:
- **Point 1:** Likely represents a different combination of resistance and reactance, not matching our calculated values.
- **Point 7:** Would have different real and/or imaginary components, not matching 300 + j396.5.
- **Point 8:** Also represents a different impedance, not corresponding to our calculated values.

By understanding how to calculate and plot impedance, you can determine the correct point on the graph that represents the given circuit's impedance.