Question

Which of the following statement is correct for EM wave:

• A. Velocity in vacuum is \( 3 \times 10^6 \, \text{cm/s} \)
• B. They can travel in vacuum
• C. Energy density of electric field and magnetic field are different
• D. It contains electric field vibration only
• E. It contains magnetic field vibration only

Hint:

EM waves can travel in a vacuum and propagate at the speed of light (\( 3 \times 10^8 \, \text{m/s} \)) without requiring any medium.

Answer 1

The Correct Option is B

Electromagnetic (EM) waves are oscillating electric and magnetic fields that propagate through space. They are capable of traveling in a vacuum and do not require a medium. The speed of EM waves in a vacuum is approximately \( 3 \times 10^8 \, \text{m/s} \), which is the speed of light. Therefore, the statement about the velocity being \( 3 \times 10^6 \, \text{cm/s} \) is incorrect, as this value is much slower than the actual speed of light. Step 1: EM waves in a vacuum.
EM waves, including light, radio waves, and X-rays, can travel in vacuum, and they propagate through space with the speed of light, which is approximately \( 3 \times 10^8 \, \text{m/s} \).
Step 2: Energy density.
In an EM wave, the energy density of the electric field and the magnetic field is the same, and both fields oscillate at the same frequency and are perpendicular to each other.
Step 3: Vibration in EM waves.
Both electric field and magnetic field oscillate in an EM wave. The wave contains vibrations in both the electric and magnetic fields, not just one.
Step 4: Conclusion.
The correct statement is that EM waves can travel in a vacuum, which corresponds to option (B).
Final Answer: (B) They can travel in vacuum