(a) What is the principle upon which the lighting in fluorescent tubes operate? (b) State two factors which determine the colour of projection, g the accele...
Question 1 Report
(a) What is the principle upon which the lighting in fluorescent tubes operate?
(b) State two factors which determine the colour of projection, g the acceleration of free fall due to gravity light from a fluorescent tube
Answer Details
(a) Principle of the fluorescent tube
It works on the principle of fluorescence. An electric discharge is passed through mercury vapour in the tube; the excited mercury atoms emit mostly ultraviolet radiation. This ultraviolet light strikes the phosphor (fluorescent) powder coating the inside of the tube, which absorbs it and re-emits the energy as visible light.
(b) Two factors that determine the colour of the emitted light
- The nature (chemical composition) of the phosphor coating on the inside of the tube.
- The type of gas or vapour enclosed in the tube. (The energy/wavelength of the exciting radiation is also acceptable.)
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