Radio waves travel faster. Infrared waves travel faster. They both travel at the same speed. The wave speed varies with their frequency.
I gave my students this multiple choice question: How does the speed of radio waves compare with the speed of infrared waves?

Only one answer is correct among these 4 choices:
- Radio waves travel faster.
- Infrared waves travel faster.
- They both travel at the same speed.
- The wave speed varies with their frequency.

Could you tell me which one is correct?

They both travel at the same speed.