Question

Which of the following is not true for electromagnetic waves?

• A. They transport energy.
• B. They have momentum.
• C. They travel at different speeds in air depending on their frequency.
• D. They travel at different speeds in medium depending on their frequency.

Answer 1

The correct option is C They travel at different speeds in air depending on their frequency.

Electromagnetic wave have constant velocity in a particular medium and it is independant of frequency and it is equal to $V=\sqrt{\frac{1}{{\mu }_0{ϵ}_0}}=3\times {10}^{8}m/s$

Option C