*Question G9A10:
What standing wave ratio results from connecting a 50-ohm feed line to a 10-ohm resistive load?*  

*Correct Answer is  D: 5:1*  

### AI Response: (may contain errors)  

To determine the standing wave ratio (SWR) when connecting a 50-ohm feed line to a 10-ohm resistive load, we can use the formula for SWR:

$$
SWR = \frac{Z_L + Z_0}{Z_L - Z_0}
$$

where:
- $Z_L$ = load impedance (10 ohms)
- $Z_0$ = characteristic impedance of the feed line (50 ohms)

Substituting the values into the formula:

$$
SWR = \frac{10 + 50}{10 - 50} = \frac{60}{-40} = -1.5
$$

Since SWR is always expressed as a positive ratio, we take the absolute value of the denominator:

$$
SWR = \frac{60}{40} = 1.5
$$

However, this is incorrect. Let's recalculate:

1. **Correct Calculation**:
   - $Z_L = 10 \, \Omega$
   - $Z_0 = 50 \, \Omega$

Using the formula:

$$
SWR = \frac{Z_L + Z_0}{Z_L - Z_0} = \frac{10 + 50}{10 - 50} = \frac{60}{-40} = -1.5
$$

This indicates a mismatch, and we need to consider the absolute values:

$$
SWR = \frac{60}{40} = 1.5
$$

This is incorrect. Let's use the correct approach:

2. **Using the Reflection Coefficient**:
   The reflection coefficient ($\Gamma$) can also be used to find SWR:

$$
\Gamma = \frac{Z_L - Z_0}{Z_L + Z_0}
$$

Substituting the values:

$$
\Gamma = \frac{10 - 50}{10 + 50} = \frac{-40}{60} = -\frac{2}{3}
$$

Now, the SWR can be calculated from the reflection coefficient:

$$
SWR = \frac{1 + |\Gamma|}{1 - |\Gamma|} = \frac{1 + \frac{2}{3}}{1 - \frac{2}{3}} = \frac{\frac{5}{3}}{\frac{1}{3}} = 5
$$

Thus, the SWR is 5:1.

### Explanation of Choices:
- **Correct Answer (D: 5:1)**: This is the correct SWR calculated from the load and feed line impedance.
  
- **Incorrect Choices**:
  - **A: 2:1**: This would imply a smaller mismatch, which is not the case here.
  - **B: 1:2**: This suggests a very low SWR, indicating a good match, which is incorrect.
  - **C: 1:5**: This is also a low SWR, indicating a good match, which does not apply to a 10-ohm load on a 50-ohm line.

### Summary:
- The SWR of 5:1 indicates a significant mismatch between the 50-ohm feed line and the 10-ohm load.
- Understanding how to calculate SWR using both the impedance ratio and reflection coefficient is crucial for the exam.