Photovoltaics Discovered In 1875
These days we are celebrating the UN’s 2015 Year of Light. Physicist John Perlin explains an excellent archive for any person wishing to keep abreast of today’s solar revolution.
The year: 1872. It was this discovery that stirred keen interest in two British scientists, William Grylls Adams and Richard Evans Day. Adams and Day had received from Smith the bars of selenium he had experimented with. Their goal? To delve deeper into the peculiar behavior Smith had discovered.
In one experiment, Adams and Day passed a battery-generated current through the bars. After detaching the battery from the selenium, they discovered to their astonishment that the induced current had reversed itself. To see if light would have the same effect as the battery had, the the two scientists placed candlelight close to the selenium. The flame forced the current to flow in the opposite direction as if it were a battery.
They therefore knew they had discovered something previously unknown to science – that a current could be started by the action of “light alone” in a solid-state material.The two scientists called the flow of electricity caused by light, “photoelectric.” Today, we say, “photovoltaic.” So began in 1875 the first stirrings of today’s solar revolution.
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Image credit John Perlin: Let It Shine