*Question E8B03:
What is the modulation index of an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency if the highest modulating frequency is 1000 Hz?*  

*Correct Answer is  A: 3*  

### AI Response: (may contain errors)  

To find the modulation index ($\mu$) of an FM signal, we use the formula:

$$
\mu = \frac{\Delta f}{f_m}
$$

where:
- $\Delta f$ = maximum frequency deviation (in Hz)
- $f_m$ = highest modulating frequency (in Hz)

In this case:
- The maximum frequency deviation $\Delta f$ is 3000 Hz.
- The highest modulating frequency $f_m$ is 1000 Hz.

Now, substituting the values into the formula:

$$
\mu = \frac{3000 \, \text{Hz}}{1000 \, \text{Hz}} = 3
$$

### Explanation of the Correct Answer:
- The correct answer is **3** because the modulation index is calculated as 3, indicating that the frequency deviation is three times the highest modulating frequency.

### Explanation of Incorrect Choices:
- **Choice A: 3** - This is the correct answer.
- **Choice B: 0.3** - This would imply a much smaller frequency deviation relative to the modulating frequency, which is not the case here.
- **Choice C: 6** - This would suggest that the frequency deviation is six times the modulating frequency, which is incorrect based on the given values.
- **Choice D: 0.6** - Similar to choice B, this indicates a much smaller deviation than what is provided.

### Summary:
- The modulation index is a key parameter in FM transmission, indicating how much the carrier frequency varies in response to the modulating signal.
- The formula used is straightforward and essential for calculating the modulation index in FM signals.