What is the speed of radio waves?

What is the speed of radio waves?

• A. 186,000 miles per second
• B. 300,000 kilometers per second
• C. 186,000 miles per hour
• D. 3,000 kilometers per second

Answer: (A)

Radio waves are electromagnetic waves, so they travel at the speed of light in free space. That speed is about 299,792 kilometers per second, which is roughly 186,282 miles per second. In practical terms, we round that to about 186,000 miles per second or 300,000 kilometers per second. The speed is essentially the same in air, with only a tiny reduction due to the medium’s refractive index. The choice given in miles per second matches this familiar value, making it the best answer. The other options mix units or are off by an order of magnitude—for example, miles per hour is far too slow, and 3,000 kilometers per second is much lower than the speed of light.

Radio waves are electromagnetic waves, so they travel at the speed of light in free space. That speed is about 299,792 kilometers per second, which is roughly 186,282 miles per second. In practical terms, we round that to about 186,000 miles per second or 300,000 kilometers per second. The speed is essentially the same in air, with only a tiny reduction due to the medium’s refractive index.

The choice given in miles per second matches this familiar value, making it the best answer. The other options mix units or are off by an order of magnitude—for example, miles per hour is far too slow, and 3,000 kilometers per second is much lower than the speed of light.