Thursday, 15 September 2016

electromagnetism - Why aren't solenoid/electromagnet windings insulated?


This has been bugging me for a long time. Take this video for example.


I have always thought that electricity will take the shortest path. When the electromagnet's windings are uninsulated, it seems that the electricity would flow straight through the "mass of metal" created by the wire, not in the circular path needed for the electromagnet to work. I have also seen solenoids that work like this. How does this design work?



Answer



It is insulated. Have you ever noticed that sometimes solenoids are made from copper wire that seems distinctly non copper coloured?


Red solenoid


This is called enamelled copper wire, and it available in a whole range of colours.


enamelled copper wire


The insulation is just a very thin coating of polyurethane, polyamide or polyester. It shouldn't be confused with vitreous enamel, which is glass. The good thing about it is that you can easily remove the insulation by rubbing hot solder on the wire.


Tinning enamelled copper wire



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