In 1850 #LeonFoucault adapted the experiment #CharlesWheatstone devised to measure the #SpeedofElectricity to determine the #SpeedofLight. Nobody knew - light is just another electromagnetic wave that moves at similar speeds to electricity in a wire. It took another 15 yrs before #JamesClerkMaxwell formed the principles of #Electromagnetism which underpins modern electronics.
In Source: Science Museum
