Which type of waves do not require a medium?

Electromagnetic waves are unique because they do not require a medium to travel. This characteristic allows them to propagate through a vacuum, such as space, where no matter is present. Electromagnetic waves, which include visible light, radio waves, X-rays, and microwaves, consist of oscillating electric and magnetic fields that can travel through empty space.

In contrast, sound waves and mechanical waves depend on a medium (such as air, water, or solid substances) to carry energy. Sound waves travel through vibrations in air molecules or other materials, while mechanical waves, which include both transverse and longitudinal waves, require a medium to facilitate the propagation of their energy.

Longitudinal waves are a specific type of mechanical wave in which the particle displacement is parallel to the direction of wave propagation. Since longitudinal waves fall under the broader category of mechanical waves, they also require a medium to travel, further emphasizing why electromagnetic waves stand out as the only option that can move through a vacuum.