GEOLOGY

Detailed explanation-1: -A magnetic field is generated by an electric current. While an electric charge is moving, this is possible. The magnetic field is not generated when the electric charge is at rest. The magnetic field is generated when the atom spins and orbits the nucleus.

Detailed explanation-2: -Alternating electric current flows through the solenoid on the left, producing a changing magnetic field. This field causes, by electromagnetic induction, an electric current to flow in the wire loop on the right.

Detailed explanation-3: -There is an electric current in a wire because there is an electric field inside the wire. It’s this electric field that pushes the free electrons to get them to move along.

Detailed explanation-4: -An electric field is produced when the charge is stationary with respect to an observer measuring the properties of the charge, and a magnetic field as well as an electric field is produced when the charge moves, creating an electric current with respect to this observer.