Artificial Magnet

Principle of Artificial Magnet:

               When electrical current passes through a coil, magnetic field will be induced by the electrical current around the coil. Usually, different materials are put into the coil to intensify the magnetic field.

              Consider the following setup: a power source connecting to the wire winding as a coil,  and a switch to turn on or turn off the power.  Put different materials ( like nails, iron core ) inside the coil to find out which material would have the strongest magnetic field.