Which type of wave does NOT require a medium to travel?

The correct answer is light wave because it is classified as an electromagnetic wave, which does not need a medium to propagate. Unlike mechanical waves, which require a physical medium such as air, water, or solids to travel through, light waves can move through the vacuum of space. This characteristic allows light from the Sun to reach Earth despite the vast emptiness of space in between.

In contrast, mechanical waves, sound waves, and pressure waves all depend on a medium to convey their energy. Mechanical waves include both sound and pressure waves, which necessitate a material medium to transmit the vibrations that create the wave. Sound waves specifically require a medium like air or water to be heard, and pressure waves function similarly by requiring matter to carry the fluctuations in pressure.

Understanding the distinction between these types of waves is fundamental in physics, particularly in the study of wave properties and behaviors in different environments.