Approximately how fast do radar waves travel in air?

Approximately how fast do radar waves travel in air?

• A. 100,000 miles per second
• B. 186,000 miles per second
• C. 187,000 miles per second
• D. 300,000 miles per second

Answer: (C)

Radar waves are electromagnetic waves, so they travel at the speed of light in the medium they move through. In air, this speed is very close to the vacuum value because air’s refractive index is only a little above 1. Using v = c/n with c about 186,000 miles per second in vacuum and n roughly 1.0003 for air gives a speed around 186,000 to 187,000 miles per second. Using the rounded figure of 187,000 miles per second keeps calculations simple while still being a good approximation for rough radar range estimates. This near-light-speed behavior is why radar ranges are derived from time-of-flight using essentially the speed of light, with only tiny adjustments for air conditions.

Radar waves are electromagnetic waves, so they travel at the speed of light in the medium they move through. In air, this speed is very close to the vacuum value because air’s refractive index is only a little above 1. Using v = c/n with c about 186,000 miles per second in vacuum and n roughly 1.0003 for air gives a speed around 186,000 to 187,000 miles per second. Using the rounded figure of 187,000 miles per second keeps calculations simple while still being a good approximation for rough radar range estimates. This near-light-speed behavior is why radar ranges are derived from time-of-flight using essentially the speed of light, with only tiny adjustments for air conditions.