Consider the following statements regarding Electromagnetic Waves:1.Electromagnetic waves propagate in free space without requiring a material medium.2.Electric and magnetic fields in EM wave are perpendicular to each other.3.Wave velocity in free space is equal to speed of light.4.EM waves cannot propagate in vacuum.Which of the above statements is/are correct?

Correct Answer: A - 1, 2 and 3 only

Quick Concept Explanation

A plane electromagnetic wave can propagate through vacuum without a material medium. In a homogeneous lossless medium, wave speed and intrinsic impedance are set by permittivity and permeability; in free space they reduce to c and about 377 ohms. Key relation: v=1/√(με); η=√(μ/ε); in free space c≈3×10^8 m/s and η0≈377 Ω.

Exam focus: Remember the orthogonal E-H-propagation triad. Common trap: In the elementary nondispersive model, wave speed is not set by frequency.

Statement-wise Verification

• Statement 1 - Correct.
  Electromagnetic waves propagate in free space without requiring a material medium.
  A plane electromagnetic wave can propagate through vacuum without a material medium.
• Statement 2 - Correct.
  Electric and magnetic fields in EM wave are perpendicular to each other.
  Its electric and magnetic fields are mutually perpendicular and perpendicular to the propagation direction.
• Statement 3 - Correct.
  Wave velocity in free space is equal to speed of light.
  In a homogeneous lossless medium, wave speed and intrinsic impedance are set by permittivity and permeability; in free space they reduce to c and about 377 ohms.
• Statement 4 - Incorrect.
  EM waves cannot propagate in vacuum.
  The correct principle is: A plane electromagnetic wave can propagate through vacuum without a material medium.

Core Concept

A plane electromagnetic wave can propagate through vacuum without a material medium. Its electric and magnetic fields are mutually perpendicular and perpendicular to the propagation direction. In a homogeneous lossless medium, wave speed and intrinsic impedance are set by permittivity and permeability; in free space they reduce to c and about 377 ohms.

Formula / Key Relationship

v=1/√(με); η=√(μ/ε); in free space c≈3×10^8 m/s and η0≈377 Ω.

Why the Other Options Are Wrong

Option B is incorrect because it includes incorrect statement(s) 4 and omits correct statement(s) 2, 3. Option C is incorrect because it omits correct statement(s) 1. Option D is incorrect because it includes incorrect statement(s) 4.

Exam Shortcut / Approach

Remember the orthogonal E-H-propagation triad.

Common Mistake

In the elementary nondispersive model, wave speed is not set by frequency.

Quick Revision

Propagation in Free Space is linked with Plane EM Waves, Electromagnetic Waves and Electromagnetic Fields. Remember the orthogonal E-H-propagation triad.