how all EM waves travel wit the same speed?

Answer 1

I disagree with the previous person who replied, who compared light and sound waves, while you were clearly asking about EM waves.

EM waves indeed all travel at the speed of light - same speed. As with all laws of nature, we don't have a clear-cut answer for this one, we just see things the way they are and describe them, without finding any metaphysical reasons for it.

The result of EM waves traveling at the speed of light is clearly shown in Maxwell's Equations. It was then asked "compared to what", a question that was tested on the Michelson Morley experiment and explained by Einstein, who made the speed of light a very important property in nature.

That said, speed of light in matters varies by the refraction coefficient of the material in question. However, that's not the actual speed of light, but rather the photos interact with the atoms, get absorped, and then re-emitted, hence their effective speed is smaller.

Answer 2

EM waves are a form of light. Some frequencies you can see, like red and orange, and other frequencies you can't, like radio waves and x-rays. The speed of travel does not depend on the frequency.
Think of sound: a flute is high frequency, and a tuba puts out low frequencies. Imagine listening to a marching band a distance away. If, say, low frequencies travelled faster than high frequencies, you would hear the tuba playing at a different place in the song than the flute! The flute might be on the second bar of the piece, yet you hear the tuba playing a note from the third bar. Lucky sound waves travel the same speed, no matter what frequency. Same with light (EM.)

Answer 3

All EM waves are predicted by Maxwell's equations. There are two terms included in the equation. There is the permittivity (associated with the electric field) and permeability (associated with the magnetic field). The speed of the waves is 1 divided by the square root of the two constants multiplied together. The speed is not a function of frequency; only the two physical constants.

Answer 4

Electromagnetic waves speed depends on the medium which it travels through and the nature of the wave. For example, light and sound travel at different speeds through air.

Answer 5

Electromagnetic waves include radio, microwave, infrared, light, ultraviolet, xray and gamma. All are different wavelengths of the spectrum.
speed =frequency x wavelength.

They travel at the same rate through the same medium because they are different sizes of the same group of waves.