1.Why is a copper wire was used in a solenoid rather than a iron wire ?
Don't you have any ideas of your own? What differences are there, in electrical properties, between copper and iron? (Gold is even better but expensive!)
well simply because copper has lower resistance than iron. thus with more electricity flowing through(copper), u can generate a stronger magnetic field.
I'm sure you mean current.
The comments already given about resistance are certainly correct. Because the magnetic field of a solenoid depends on the number of turns per unit length of the solenoid, it can be important to have the windings as tightly spaced as possible - which means making them as thin as possible. Since the electrical conductivity of copper is higher than steel, copper wires can be thinner.
There is also the problem of insulating steel and the deterioration of steel through oxidation (rust). A thin varnish coating on copper will create a good permanent insulaton. Steel electrical wire is often copper coated for this reason. Steel has the advantage that it is stronger than copper. So if strength is important, you may want to use copper coated steel wire for the solenoid.
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