How does electromagnet work and what …

A simple electromagnet consisting of a coil of insulated wire wrapped around an iron core. A core of ferromagnetic material like iron serves to increase the magnetic field created.  The strength of magnetic field generated is proportional to the amount of current through the winding. Take around 75 cm long piece of insulated   flexible wire and an iron nail.  Wind the wire tightly around the nail in the form of a coil. Connect the free ends of the wire to the terminals of a cell through a switch. Place some pins on or near the end of the nail. Now switch on the current and the pins cling to the tip of the nail.  Switch off the current. The coil in the above activity behaves like a magnet when electric current flows through it. When the electric current is switched off, the coil generally loses its magnetism. Such coils are called electromagnets. The electromagnets could be made strong by increasing the number of turns in the coil and by increasing the current passing through the coil.