Question

Why we use insulated copper wire while making a solenoid, electric motor or a generator? What if we use a naked wire instead?

Answer 1

For making the coils we use insulated copper wire because insulated wires acts like a different wires, i.e. no of turns will be more and magnetic field will be stronger.
But when wire is not insulated, all turns will act like a one single copper wire and magnetic field produced will be less.