Electro-magnets are created
a) applying a charge to a magnetic material, wrapped in an insulator, which creates an electro magnetic field around the magnet.
b) covering a magnet with insulation in applying an alternating electrical current to the magnet.
c) twisting a ferromagnetic material, wrapping in an insulator, and applying a direct current to the coil.
d) wrapping in insulated wire around a medal with ferromagnetic properties and applying an electric current.

Wrapping in insulated wire around a medal with ferromagnetic properties and applying an electric current

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.