When the particles of a wave are far apart, the wave is considered to have a low amplitude.

Here's why:

* Amplitude refers to the maximum displacement of a particle from its rest position as the wave passes through.

* High amplitude means the particles are displaced a large distance from their rest position, resulting in a more intense wave.

* Low amplitude means the particles are displaced a small distance from their rest position, resulting in a less intense wave.

So, when particles are far apart, it means their displacement from their rest position is small, resulting in a low amplitude wave.