The Hebrew word hashmal, used in Ezekiel‘s vision of the Chariot (Ezekiel 1:4, 27), is usually translated as ‘amber’ or ‘electrum’ and may be based on the recognition by the ancients that rubbing amber produces sparks.
This word is, in fact, used for ‘electricity’ in modern Hebrew. Israeli children are astonished to find, as they think, that the prophet knew of electricity! Once this mysterious power was discovered and harnessed to cater to human needs, a host of problems became acute in connection with Jewish religious law. With regard to the Sabbath, for instance, on which the law forbids kindling fire (Exodus 35: 3), the question arose of whether this meant that it was wrong to switch on an electric light on the Sabbath.
In the early days, some Rabbis tried to argue that electric lights may be switched on on the Sabbath, since there is no combustion in the filament and, in any event, the electric power is already present, the switching-on of the light being only an indirect cause. Conservative Jews accept this argument and permit the swittching-on of electric lights but do not allow cooking by electricity on the Sabbath, since to cook food is a separate prohibition. In the Reform system there is generally a relaxation of the strict Sabbath laws. Orthodox Judaism today does not permit any use of electricity on the Sabbath. Orthodoxy sees it as wrong not only to switch on electric lights but even to open the door of a refrigerator so that the light will come on.
Most Orthodox authorities today also ban the use of a microphone or a telephone on the Sabbath on the grounds that sparks are produced and that the flow of the current is chanced through the speaking voice.