Mechanical waves have a crest but no trough is a characteristic of a mechanical wave but not a characteristic of an electromagnetic wave.
The waves that are related to both electricity and magnetism are known as electromagnetic (EM) waves. These waves are made up of time-varying electric and magnetic fields that travel over space.
Mechanical waves have a peak but no dip, which is a mechanical wave characteristic but not an electromagnetic wave characteristic.
Hence, mechanical waves have a crest but no trough is a characteristic of a mechanical wave but not a characteristic of an electromagnetic wave.
To learn more about the electromagnetic wave refer to the link;
https://brainly.com/question/8553652
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