Radioactive Exit Sign Handling

As a source of what can be described as perpetual light, the radioactive exit sign has not been linked to production of any one particular hue. In fact the color of its glow depends on the exact nature of the chemical that has been placed inside of the sign’s thick glass tube. Still, more than one chemist had to conduct a series of investigations, in order to provide the world with a clearer understanding of exactly what causes that glow.

Origins of the radioactivity

Two chemists, a man and a woman, devoted years to the first such investigations. Actually, their efforts had focused on isolation of the element that was believed responsible for production of the radiating energy that came from a certain ore. Their attempt to isolate that element included the fractional crystallization of material that had been extracted from the same ore, something called pitchblende.


One night, after initiating one such fractional crystallization, the team of scientists that shared the last name of Curie chose to check on how far their separation procedure had progressed. In order to do that, the married pair had to return to their lab, one located in a shed, close to their home. Upon opening the shed’s door, the two noted the glowing nature of their apparatus and the other glassware in the laboratory. That glow seemed to emanate from a chemical that possessed a strange and, until then, unknown and unidentified source of power.

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At the time of its discovery, that glow’s hue was viewed as secondary to the fact that it had been observed by respected scientists. After all, there are no records that give the precise color of the flames, when mankind first discovered fire. To an untrained eye, the glowing glassware seen by the Curies might have been viewed by members of the public as a sort of miracle.

Uses of radioactivity in signage

However, trained scientists seldom explain any occurrence as proof that the world has seen a true miracle. Their follow-up investigations produced some noteworthy facts. Those facts helped to explain why a radioactive exit sign could keep glowing, and would continue to produce beams of the same hue.

Working on an exit light with radioactivity

Unlike the gases that have been put into discharge tubes, a radioactive substance does not need to feel an electrical charge in order to light up. In fact no chemical or electrical power aids the production of its glowing light. That phenomenon takes place following the movement of electrons within the atom of a radioactive material. One or more electrons move from a higher spin level to a lower one, one closer to the atom’s nucleus.

Features and aspects

That explanation points to the existence within any element of two different aspects. One aspect relates to the changes that take place during a chemical reaction. The production of different-colored flames serves as proof that each element has a characteristic way of demonstrating its possession of that one aspect, one of the two associated with all elements.

The second aspect possessed by every element is one that remained hidden to men’s eyes for many centuries. Isolation of radium by the Curies, aided considerably the identification of that aspect. It concerns an atom’s fundamental properties. Once altered, it can change more than the color produced during a reaction; it manages to transform an atom’s identity.

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