(a) What is the principle upon which the lighting in fluorescent tubes operate? (b) State two factors on which the colour of light from a fluorescent tube d...
(a) What is the principle upon which the lighting in fluorescent tubes operate?
(b) State two factors on which the colour of light from a fluorescent tube depends.
(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 ultraviolet radiation. This ultraviolet light strikes the fluorescent (phosphor) powder coating the inside of the tube, which absorbs the invisible ultraviolet and re-emits the energy as visible light.
(b) Two factors on which the colour of the light depends:
The nature (chemical composition) of the fluorescent powder (phosphor) coating the tube.
The nature of the gas or vapour (and the pressure) inside the tube.
(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 ultraviolet radiation. This ultraviolet light strikes the fluorescent (phosphor) powder coating the inside of the tube, which absorbs the invisible ultraviolet and re-emits the energy as visible light.
(b) Two factors on which the colour of the light depends:
The nature (chemical composition) of the fluorescent powder (phosphor) coating the tube.
The nature of the gas or vapour (and the pressure) inside the tube.