Amplitude of a longitudinal wave is measured as a change in pressure.
rarefraction
Puss on you
rarefraction
Condensation is the increase in density in a longitudinal wave, thus it signifies a high pressure area, which is higher energy, which is equated to the crest of a transverse wave.
Sound waves are longitudinal.
Compression
Radio wave is not a longitudinal wave it is a transverse wave
Longitudinal Wave
A longitudinal wave is a wave in which the particles of the wave vibrate/oscillate in the same direction as the direction of propagation of the wave.They are formed by alternate compressions and rarefactions in the wave medium. There is an increase in pressure at the compressions and a decrease in pressure at the rarefactions. Hence, they are also called pressure.A sound wave is an example of a longitudinal wave.(check the related link for an illustration)
A sound wave is indeed a longitudinal wave as opposed to a transverse wave
a longitudinal wave is a vibration like sound therfore a longditudinal wave is a sound. The pressure Vibrations of frequency between 16 - 20000 hertz, which propagates in medium we perceive as a sound. But longitudinal mechanical wave is not necessarily sound - for example wave along the spring, or density waves forming spiral structure of galaxies!