T3B11 What is the approximate velocity of a radio wave as it travels through free space?
A. 3000 kilometers per second
B. 300,000,000 meters per second
C. 300,000 miles per hour
D. 186,000 miles per hour
- B. 300,000,000 meters per second
- All electromagnetic energy — radio waves, light, X-rays — travels at the speed of light. In a vacuum, the speed of light (represented by a lower-case c) is 300,000,000 meters per second. It travels close to that speed in air. In denser materials such as water or glass, and in cables, light travels slower. [Ham Radio License Manual, page 2-4]