In a vacuum, at what speed does electromagnetic radiation of every frequency travel?
AIt varies from wave to wave depending on colour
B3.00 x 10^8 m/s, the same for every frequency
CIt depends only on the size of the source
D1.50 x 10^8 m/s, half the usual quoted value
Answer & Solution
Correct answer: B. 3.00 x 10^8 m/s, the same for every frequency
1. All electromagnetic radiation travels at the same speed in a vacuum, regardless of frequency.
2. That speed is 3.00 x 10^8 m/s, given the symbol c.
3. A value that depends on colour or on source size contradicts this single fixed speed.
_Source: OpenStax Physics (CC BY 4.0), Ch 15 "Light", section 15.2 The Behavior of Electromagnetic Radiation_
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