Question

1) What happens when an electric current is applied to a wire?​

Answer 1

This is a rather vague question, but to answer briefly..

When you say supply electric current, it means there a potential difference applied across the ends of the wire, causing the electrons in the wire to move against the potential difference. Hence, a current is induced in the direction of the potential difference, the electric current.

As time progresses, due to the resistance present in the wire (every material posses some resistance) , there is eventually a heat generated according to the relation:

H=I^2Rt , for a constant supply of current.

Answer 2

An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance.