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૧૦. ટ્યૂબ લાઇટની પ્રક્રિયા
ટ્યૂબ લાઇટમાં કેવી રીતે પ્રકાશ પેદા કરાય છે, એ વિષયમાં ઇન્ટરનેટથી ઉપલબ્ધ સામગ્રીને અહીં પ્રસ્તુત કરવામાં આવી છે. એની સાથે ફ્લોરેસેન્ટ લાઇટ, નિયોન લાઇટ વગેરેમાં શું અંતર છે, એ પણ સ્પષ્ટ થઈ રહ્યું છે.
"A neon light is the sort you see used in advertising signs. These signs are made of long, narrow glass tubes, and these tubes are often bent into all sorts of shapes. The tube of a nepn light can spell out a word, for example. These tubes emit light in different colours. A fluorescent lights in offices, stores and some home fixtures.
The idea behind a neon light is simple. Inside the glass tube there is a gas like neon, argon or krypton at low pressure. At both ends of the tube there are metal electrodes. When you apply a high voltage to the electrodes, the neon gas ionized and electrons flow through the gas. These electrons excite the neon atoms and cause them to emit light that we cans see. Neon emits red light when energized in this way. Other gases emit other colours.
A fluorscent light works on a similar idea but it has an extra step. Inside a fluorscent light is low-pressure mercury vapor. When inized, mercury vapor emits ultraviolet light. Human eyes are not sensitive to ultraviolet light (although human skin is - see How Sunburns and Sun Tans Work). Therefore, the inside of a fluorscent light is coated with a phosphor. A phosphor is a substance that can accept energy in one form (for example, energy from a highspeed electron as in a TV tube - see How Television works) and emit the energy in the form of visible light. In a fluorescent lamp, the phosphor accpets the energy of ultraviolet photons and emits visible-photons.
The light we see from a fluorescent tube is the light given off by the phosphor that coats the inside of the tube (the phosphor fluoresces when energized hence the name). The light of a neon tube is the colored light that the neon atoms give off directly.
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