copper coil: do you need to actually turn around a wire many many times or can you just take a copper tube?
You need 2 things: baking soda and lemon juice. Use the baking soda to scrub off any grease and then rub with lemon juice (after rinsing) and buff dry.
vinegar and baking sodatry it with a penny you will be amazed
If your looking for magnetic inductance. IE, transformers, electromagnets, etc. You have to wind it with insulated wire. Electricity follows the path of least resistance so a tube would be one single wire it would just go straight through it in a line. A coil is going to force the electricity to follow the path of a circle.
