The thing that is not necessary in the transfer of energy by electromagnetic waves is a material medium (matter).

Quick Scoop

  • Electromagnetic waves (like light, radio waves, and X‑rays) can travel through a vacuum such as outer space.
  • That means they do not need air, water, or any other substance to carry their energy.
  • They transfer energy via oscillating electric and magnetic fields, not by vibrating particles of matter.

So, in exam-style wording:

What is not necessary in the transfer of energy by electromagnetic waves?
A material medium (matter / particles / molecules) is not necessary.

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