Maxwell predicted the existence of EM waves before they were even discovered. In the 1860's, he showed theoretically that all EM waves should travel at the same speed in a vacuum, c.
- c = the speed of the wave in ms^-1 = 3.00 x 10^8 ms^-1
- Uo = the permeability of free space = 4Pie x 10^-7 Hm^-1
- Eo = the permittivity of free space = 8.85 x 10^-12 Fm^-1
- Uo relates to magnetic flux density due to a current-carrying wire in free space.
- Eo relates to electric field strength due to a charged object in free space.
By the time Maxwell did this calculation, the velocity of light could be measured quite accurately, and it was found to be very close to Maxwell's value of c.
This suggested that light was an electromagnetic wave.
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