A magnet gives rise to a field in the space that surrounds it. The field tells a compass needle which way to point, and causes forces on other magnets, iron and steel objects, and current- carrying wires. The parts of a magnet where the field emerges is called the N pole, and where the field enters the magnet is called the S pole. Magnets always have both N and S poles.

It takes energy to make a magnetic field. We can use this idea to explain the magnetic force.

When we turn off the current to an electromagnet, the magnetic energy will keep the current going briefly, and in the process may give rise to an unusually high voltage in the circuit or even a voltage in a different circuit.

We found that there are materials that are themselves magnetic (permanent magnets), and materials that only become magnetic in the presence of other magnets. We can also produce a magnetic effect with a current carrying wire.

Electricity is related to magnetism in several ways. A current gives rise to a magnetic field, and a magnetic field gives rise to a force on a current. A rapidly changing magnetic field gives rise to an electrical effect that will make currents flow.

We have studied several electrical components:

• Electromagnet. A current gives rise to a magnetic field, which we can make bigger by making a coil and by wrapping it around a steel or iron object.
• Buzzer. The kind we have in our kit combines an electromagnet with a circuit to turn the magnet on and off. It is one of several ways to make sound using an electrical signal.
• Motor. By turning a magnet on and off, we can provide an alternating force that will make a rotor go around.