Which of the following is an example of a mechanical wave?

• A. Light waves
• B. Radio waves
• C. Gamma rays
• D. Ocean waves

Answer: (D)

The concept here is that a mechanical wave must have a medium through which to carry energy. In a mechanical wave, the particles of the medium vibrate or move as the wave passes, transferring energy from one place to another. Ocean waves illustrate this perfectly: the water surface moves up and down and the water particles oscillate as the wave travels across the sea, so the energy moves while the water itself shifts around.

In contrast, electromagnetic waves—like light, radio waves, and gamma rays—do not require a medium; they can propagate through empty space by oscillating electric and magnetic fields. That’s why they can reach us from the sun or from distant galaxies even though there’s no material medium in between.

So ocean waves are the example of a mechanical wave because they rely on the motion of the medium (water) to carry energy.