Question

The CORRECT statement among the following regarding electromagnetic waves is

• A. They can travel through vacuum
• B. They consist of only electric field
• C. They consist of only magnetic field
• D. They require a medium to propagate
• E. They move with a velocity of $3 \times 10^8 \text{ cms}^{-1}$

Hint:

Remember: EM waves are transverse in nature and propagate through vacuum at the speed of light. Light itself is an EM wave!

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Electromagnetic (EM) waves are oscillations of electric and magnetic fields that propagate through space. Unlike mechanical waves, they do not require a material medium to travel.

Step 2: Detailed Explanation:
1. Nature of Propagation: EM waves are produced by oscillating charges and consist of time-varying electric and magnetic fields perpendicular to each other and to the direction of propagation.
2. Medium Requirement: Because they are self-sustaining oscillations of fields, they can travel through empty space (vacuum). Mechanical waves like sound need a medium, but EM waves do not.
3. Components: Statement (B) and (C) are incorrect because an EM wave must have both electric and magnetic components.
4. Velocity: In vacuum, EM waves travel at $c = 3 \times 10^8 \text{ ms}^{-1}$. Statement (E) gives the speed as $3 \times 10^8 \text{ cms}^{-1}$, which is $3 \times 10^6 \text{ ms}^{-1}$—incorrect. (The speed in cm/s is $3 \times 10^{10} \text{ cms}^{-1}$).

Step 3: Final Answer:
The correct statement is that they can travel through vacuum.