Answer :
Mechanical waves have a crest but no trough is a characteristic of a mechanical wave but not a characteristic of an electromagnetic wave.
What is 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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