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The speed of all electromagnetic waves in a vacuum is

Correct answer: A. 3 times 10 to the 8 m per second, whatever their frequency

  • A. 3 times 10 to the 8 m per second, whatever their frequency
  • B. different for each frequency
  • C. 340 m per second
  • D. dependent on the intensity

Explanation

In a vacuum every electromagnetic wave from radio to gamma travels at the same speed c, so wavelength and frequency vary inversely. In a material medium the speed falls and does depend slightly on frequency, which is the dispersion that splits white light in a prism. The value 340 m per second is the speed of sound in air.

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About Electromagnetic Waves

Electromagnetic waves consist of mutually perpendicular, oscillating electric and magnetic fields that also remain perpendicular to the direction of propagation. They travel through vacuum at the speed of light and include radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. Unlike mechanical waves, they do not require a material medium.

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