Which statement about electromagnetic waves is true?

• A. Are longitudinal waves
• B. Travels through an empty space
• C. Require a medium to travel
• D. Do not emit radiation

Answer: (B)

Electromagnetic waves propagate by changing electric and magnetic fields that sustain one another, so they don’t need a material medium to travel. In empty space, these self-sustaining fields still move, all at the speed of light, which means they can travel through what seems like nothing at all. That’s why the true statement is that they travel through empty space.

They aren’t longitudinal waves—the oscillations are perpendicular to the direction of travel, which is a hallmark of transverse waves. They don’t require a medium, so saying they need one is incorrect. And they are a form of radiation, carrying energy away as electromagnetic radiation, so the idea that they do not emit radiation isn’t accurate.