Sound is a longitudinal mechanical wave. It requires the presence of a medium; electromagnetic waves do not require a medium.
The correct answer and explanation is :
The statement is correct: Sound is a longitudinal mechanical wave, and it requires the presence of a medium, whereas electromagnetic waves do not require a medium.
Explanation:
Sound as a Longitudinal Mechanical Wave:
Sound is a type of wave that propagates through a medium (solid, liquid, or gas) by the vibration of particles in the medium. These vibrations are parallel to the direction of wave propagation, making sound a longitudinal wave. In longitudinal waves, regions of compression (where particles are close together) and rarefaction (where particles are farther apart) move through the medium as the wave travels. The speed at which sound travels depends on the properties of the medium, such as its density and elasticity.
For example, sound travels faster through solids (like steel) than through liquids (like water) and slower through gases (like air). In space, where there is no air or any other medium, sound cannot travel, as there are no particles to vibrate and carry the wave.
Electromagnetic Waves:
Electromagnetic (EM) waves, such as light, radio waves, and X-rays, are fundamentally different from sound. They do not require a medium for propagation; they can travel through a vacuum (empty space). EM waves are transverse waves, where the oscillations of electric and magnetic fields are perpendicular to the direction of wave propagation.
The key difference is that EM waves carry energy through the oscillations of electric and magnetic fields, which can exist and propagate through empty space. This is why light from the Sun can reach Earth across the vacuum of space.
Conclusion:
Sound waves are mechanical, meaning they rely on a medium to propagate, while electromagnetic waves can travel through a vacuum due to their oscillating electric and magnetic fields. Thus, the key distinction lies in the nature of the wave (mechanical vs. electromagnetic) and the requirement for a medium (sound vs. light).