Physics 104 Solutions Symko, Chapter 8 - Electromagnetic Waves and Tuners Questions for Review 1. Amplitude modulation refers to varying the size, or amplitude, of a carrier wave in a well-defined way, i.e. at a set of audio frequencies.
Frequency modulation refers to periodic changes in the frequency of the carrier wave.
The amplitude modulated carrier wave is amplified and fed to an antenna for broadcast. A light wave differs from a radio wave simply by the range of wavelengths into which it falls. Visible light has a wavelength of between approximately 0.4 m and 0.7 m, while radio wavelengths are much longer, in the range of meters and larger. A superheterodyne receiver combines incoming radio wave signals with the oscillations of a single-frequency local oscillator, producing beats, or amplitude fluctuations, at a range of frequencies which are simply the differences between the radio frequencies and the local oscillator frequency. This now produces an intermediate frequency carrier with the audio modulation signal, which is at a fixed frequency and can be amplified and processed by subsequent electronics.