You will need
- conductor, the magnetic needle, a permanent magnet, a coil with a core.
The creation of a magnetic field will takabonerate conductor and connect it to a power source making sure that the conductor is not overheated. Bring to him a thin magnetic needle that can rotate freely. Installing it in different points of space around the conductor, make sure that it is oriented by the magnetic field lines.
The magnetic field of the permanent will magnetoshere permanent magnet and hold it close to any object containing large amounts of iron. You will immediately see the magnetic force that attracts the magnet and iron body - this is the main proof of the existence of a magnetic field. Put a permanent magnet on a sheet of paper and sprinkle it around a small iron shavings. After some time, on a sheet of paper is drawn, showing the presence of the magnetic field lines. They are called lines of magnetic induction.
The creation of a magnetic field electromagnetically with insulated wire, attach to a source of electrical current through the rheostat. In order to avoid burning out the wires, set the rheostat at maximum resistance. Into the coil, place the magnetic. It can be a piece of soft iron or steel. If you intend to obtain a powerful magnetic field, the iron core (magnetic core) is to recruit from plates isolated each other to avoid eddy currents that will prevent the generation of a magnetic field. Connecting the circuit to the power source, start slowly moving the rheostat slider, observing that the coil winding does not overheat. The magnetic core becomes a powerful magnet, able to attract and hold a massive iron objects.