ТОР 5 статей:
While making the report he demonstrated his new device.
We examined the equipment to be introduced at this plant.
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We receive natural light from the Sun, whose surface is heated to a temperature of 10,832 degrees Fahrenheit. But visible light may be radiated by cold as well as by hot bodies.
2. Substances that transform energy into light without becoming heat are called luminofores, and the light they radiate – luminescence. There are many substances in nature that are capable of absorbing invisible ultraviolet rays and turning them into visible light.
There exist two forms of luminofores. In one case the molecules themselves have the ability of transforming absorbed energy into visible light. This group includes certain components of oil and many dyes and chemical compounds. The second group is made up of crystallized substances called phosphors including very small quantities of other substances.
4. Luminofores are widely used in modern technique, in particular in the production of luminescence lamps – a common feature of our everyday life.
Luminescence is also used in television, a luminous screen being an important part of television picture tubes. Luminofores enable also to discover and observe such radiations as ultra red, ultraviolet, X-ray and alpha that are invisible to the eye as well as fast-moving elementary particles produced by radioactive disintegration or artificial transformation of the atomic nucleus.