Question

Which of the following waves do not require any kind of medium to propagate ?

• A. Sound
• B. Earthquake wave
• C. Light wave
• D. Water surface wave

Hint:

Two main categories of waves:
{Mechanical Waves:} Need a medium (solid, liquid, or gas) to travel. Examples: Sound waves, water waves, waves on a string, earthquake waves.
{Electromagnetic Waves:} Do NOT need a medium; can travel through a vacuum. Examples: Light, radio waves, X-rays. Light from the sun reaches us through the vacuum of space, proving it doesn't need a medium.

Answer 1

The Correct Option is C

Concept: Waves can be broadly classified into two types based on their need for a medium to propagate: (A) Mechanical Waves: These waves require a material medium (solid, liquid, or gas) for their propagation. They travel by causing oscillations or vibrations of the particles of the medium. Energy is transferred through the medium. (B) Electromagnetic Waves: These waves do not require a material medium for their propagation. They can travel through a vacuum (like outer space). They consist of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of wave propagation. Step 1: Analyzing the nature of each wave type in the options
(1) Sound waves: Sound waves are mechanical waves. They need a medium (like air, water, or solids) to travel by causing compressions and rarefactions of the particles of the medium. Sound cannot travel through a vacuum.
(2) Earthquake waves (Seismic waves): Earthquake waves are mechanical waves that travel through the Earth's layers. They include P-waves (longitudinal) and S-waves (transverse), both requiring a material medium.
(3) Light waves: Light is an electromagnetic wave. Electromagnetic waves (which also include radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays) can travel through a vacuum. This is how light from the Sun reaches Earth.
(4) Water surface waves: These are mechanical waves that travel on the surface of water. They involve the motion of water particles and thus require water (a medium) to propagate. Step 2: Identifying the wave that does not require a medium From the analysis, Light waves are electromagnetic waves and do not require any kind of medium to propagate. They can travel through the vacuum of space.