Q. Consider the following statements with respect to the basic properties of the Electromagnetic Waves:

1. All electromagnetic waves – regardless of frequency – travel at speed of light through vacuum
2. All Electromagnetic waves are deflected by electric or magnetic field
3. The frequency of electromagnetic waves does not change when the medium through which the waves are propagating changes

Which among the above is / are correct statements?
Answer: Only 1 & 3
Notes: The first statement is correct and is fundamental property of the EM waves. The second statement is not correct. Third statement is correct. As waves cross boundaries between different media, their speeds change but their frequencies remain constant. Key properties of EM waves are listed below:

1. The Velocity of electromagnetic wave in vacuum is 3 × 10⁸ m / s.
2. The existence of medium is not essential for propagation.
3. In vacuum, E.M waves travel with light velocity.
4. M waves can be polarized.
5. M waves are transverse in nature.
6. M waves have momentum.
7. There is no deflection on account of magnetic or electric field.
8. They can exhibit diffraction and interference.

This question is part of UPSC Daily 20 MCQ Series Course on GKToday Android app.