Which type of waves can travel through a vacuum?

• A. Mechanical waves
• B. Electromagnetic waves
• C. Sound waves
• D. Water waves

Answer: (B)

Waves that can travel through a vacuum are electromagnetic waves. These waves propagate as fluctuating electric and magnetic fields and don’t require matter to carry them, so they can move through empty space. That’s why sunlight and radio signals can travel from the Sun to Earth and through space.

Mechanical waves, like sound, need a medium to transfer energy—vibrating particles in air, water, or solid materials carry the wave along. Without particles to interact with, sound can’t move. Water waves are disturbances that travel across the surface of water, so they also rely on a medium.