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This is the diagram out of an A level Physics book. I am sure many would agree if a student followed this diagram the tube would be damaged burning out heaters and if it did start it would draw well over the design current.
It states:-
It continues with statements like:-
This is "A" level one wonders what ordinary level students are now taught? OK maybe the student does not need to know all the information but I shudder to think what would be the result if a budding student was to try to follow the instructions given. And if the tube was around the 20W mark or less it may even fire up hope they have included a fuse?
It states:-
There is nothing about the back EMF or the current limiting qualities of the ballast.The tube has a `filament' electrode at each end. The starter unit
is necessary because the mains voltage is too small to ionise the vapour in the tube when the electrodes are cold. When the tube is first switched on, the gas (argon) in the starter 'switch' unit conducts and heats the bimetallic strip, making it bend, so the switch closes. The current through the starter unit increases enough to heat the filament electrodes. When the bimetallic switch closes, the gas in the starter unit stops conducting, and so the bimetallic strip cools and the switch opens. The mains voltage now acts between the two electrodes, which are now hot enough for ionisation of the gas to occur.
It continues with statements like:-
This is just after it has explained how the fluorescent tube contains two filaments.Did you know that the UK government is stopping the sale of filament light bulbs? We will need to use low energy light bulbs instead.
This is "A" level one wonders what ordinary level students are now taught? OK maybe the student does not need to know all the information but I shudder to think what would be the result if a budding student was to try to follow the instructions given. And if the tube was around the 20W mark or less it may even fire up hope they have included a fuse?