Which statement about electromagnetic waves is true?

Which statement about electromagnetic waves is true?

• A. They can travel through a vacuum
• B. They require a medium to propagate
• C. They are slower than sound in air
• D. They cannot be refracted

Answer: (A)

Electromagnetic waves can propagate through space without any material medium because they are oscillating electric and magnetic fields that transfer energy. This lets them travel in a vacuum, which is why sunlight and radio signals reach us from space. They move at the speed of light in vacuum—about 300,000 kilometers per second—and in air they remain incredibly fast, much faster than sound, which needs a medium to travel. Electromagnetic waves can be refracted when they move from one material to another because their speed changes with the medium, causing the path to bend. So the statement that they can travel through a vacuum is true, while saying they require a medium, that they are slower than sound in air, or that they cannot be refracted are all incorrect.

Electromagnetic waves can propagate through space without any material medium because they are oscillating electric and magnetic fields that transfer energy. This lets them travel in a vacuum, which is why sunlight and radio signals reach us from space. They move at the speed of light in vacuum—about 300,000 kilometers per second—and in air they remain incredibly fast, much faster than sound, which needs a medium to travel. Electromagnetic waves can be refracted when they move from one material to another because their speed changes with the medium, causing the path to bend. So the statement that they can travel through a vacuum is true, while saying they require a medium, that they are slower than sound in air, or that they cannot be refracted are all incorrect.