# Speed of RF waves and IR waves is same as 3 * 10 ^8 m/s?

In space,if we want to measure the speed of RF waves and IR waves it will be roughly 3 * 10^8 m/s

( SPEED OF RF WAVES = SPEED OF IR WAVES = 3* 10^8 M/S )

is this correct ?

The different in the characteristic of rf waves and ir waves is because of wavelength and frequency.

i am correct or not ?

• In vacuum with $\epsilon = 1$ for all wavelengths, the speed of light is the speed of light for all wavelengths. So, yes, rf and IR propagate together. – Jon Custer Apr 6 '16 at 17:20
• i know in normal atmosphere, there will be a refraction phenomenon that acts on both waves and the magnitude of refraction depends on wavelength and particle size ... – user143252 Apr 6 '16 at 17:28
• Which is why I specified vacuum with constant $\epsilon = 1$ for all wavelengths. In fact, the measurements of rf, ir, and visible signals from astronomical bodies provides a good test of the properties of the vacuum across very long distances. – Jon Custer Apr 6 '16 at 17:43
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## 2 Answers

In empty space their speed will be the same.

• the characteristic depends on wavelength and frequency , not on speed .. is this correct ... ?? what if we decrease the speed of rf waves by 20% .. its characteristic will remain same or not ?? – user143252 Apr 6 '16 at 17:24
• If you decrease the speed of the waves, say by having them pass into a different medium, their frequency will stay the same but their wavelength will decrease. Each wave in the old medium will produce exactly one wave in the new medium so the frequency can't change but for any wave speed = frequency x wavelength so the wavelength must change. – M. Enns Apr 6 '16 at 17:31

In a vacuum of space unaffected by any gravitational curvature or any kind of energy, the speed of an electromagnetic wave is c, 3*10^8 m/s. Radio frequency and infrared waves, have been proven by experiment to travel at the speed c.

There are two fundamental properties to any transverse wave. They are wavelength and frequency. Since the speed of an electromagnetic wave, a transverse wave, is always c, the frequency and wavelength vary depending on the type of wave we are dealing with but their products are always the same, the speed of light. That is, (Frequency of Radio Wave)(Wavelength of Radio Wave)=(Frequency of Infrared Wave)(Wavelength of Infrared Wave)=The Speed of an Electromagnetic Wave, c.

That being said, an infrared wave and a radio wave differ from each other based on their frequency and wavelength.