What does the modulation index determine in amplitude modulation?

The modulation index is a crucial parameter in amplitude modulation (AM) as it quantifies the degree of modulation applied to the carrier signal. Specifically, it measures the extent to which the amplitude of the carrier wave is varied in proportion to the amplitude of the modulating signal. A higher modulation index indicates a greater variation in the amplitude of the carrier wave, which corresponds to a stronger representation of the modulating signal in the transmitted wave.

When the modulation index is low, the changes in the carrier amplitude are minimal, and thus the modulating signal is represented less effectively. Conversely, a higher modulation index leads to a more pronounced encoding of the modulating signal within the carrier wave's amplitude variations, which is essential for effective transmission of information in AM broadcasting.

The other options do not accurately describe the role of the modulation index in amplitude modulation. For instance, signal frequency refers to the frequency of the modulated signal itself and is not influenced by the modulation index. Similarly, the type of modulation pertains to the specific scheme being used (e.g., AM versus frequency modulation) but does not relate to how much the amplitude is changing, which the modulation index directly addresses. Lastly, while the carrier wave amplitude interacts with the modulation index, the index itself specifically measures