What Is Amplitude?

Amplitude is the objective measurement of the degree of change (positive or negative) in atmospheric pressure (the compression and rarefaction of air molecules) caused by sound waves. Sounds with greater amplitude will produce greater changes in atmospheric pressure from high pressure to low pressure. Amplitude is almost always a comparative measurement, since at the lowest-amplitude end (silence), some air molecules are always in motion and at the highest end, the amount of compression and rarefaction though finite, is extreme. In electronic circuits, amplitude may be increased by expanding the degree of change in an oscillating electrical current. A woodwind player may increase the amplitude of their sound by providing greater force in the air column i.e. blowing harder.

The greater the amplitude of the wave, the higher level of energy it carries. With a sound wave, this means that the sound will be louder. With light, the bigger the amplitude means the light will be brighter. In water, the bigger the amplitude of the waves, the higher they will be.

There are several advantages of amplitude modulation, and some of these reasons have meant that it is still in widespread use today:

• It is simple to implement.
• it can be demodulated using a circuit consisting of very few components.
• AM receivers are very cheap as no specialized components are needed.