Electromagnet Activity

These activities use electricity and magnetism.

Electricity and magnetism are all around us.

Light is an electromagnetic wave.

Lightening is powerful electric current moving through the air.

The earth is a huge magnet. The magnetism is caused by motion of molten nickel and iron in the core.

Magnetite is a rock that is magnetic.

Northern lights are a beautiful light show created by sunspot activity shooting a stream of electrons and protons into outer space that upon entering the earth’s atmosphere collide with molecules causing quantum leaps and converting the kinetic energy of the electrons to light.

Electric current has a magnetic field around it. This is used to create electromagnets and electromagnetic motors. Appliances that use electricity have electromagnetic motors in them. Electromagnets are magnets that can be switched on and off by turning the current on and off. An example is the junkyard cranes that use electromagnets to lift a car and then turn the magnet off to drop the car.

Magnets ruin videotapes and cassette tapes if placed nearby. Sound and pictures are stored on magnetic tapes as magnetic fields and a magnet could change the magnetic field. Magnets may also ruin televisions and other electronic devices. Be careful where you put your magnet.

Magnets are pretty tough but the strength of the magnet could be affected by excessive heat or force.

The earth is a magnet. The core of the earth is molten iron and nickel that moves with the earth’s rotation and this movement is believed to be the cause of the earth’s magnetic field. The earth magnet has north and south poles just like the small magnets we use. Two magnets attract opposite poles and repel the same poles. This is how a compass works. The little magnet in the compass lines up with the huge but weak earth magnet.

Paper and pencil

String

Bar magnet

Draw a circle on a piece of paper. Write:

‘N’ (north) on the top of the circle.

‘S’ (south) on the bottom of the circle.

‘E’ (east) on the right side of the circle.

‘W’ (west) on the left side of the circle.

Hang a magnet over the paper. Turn the paper so the ‘N’ is under the north end of the magnet.

The magnetic field lines around a magnet can be seen by sprinkling iron filings on a sheet of paper, placing a strong magnet under the paper and tapping the paper. The lines arc from one pole of the magnet to the other. The lines are closest together at the poles of the magnet where the magnetic field is strongest.

Magnets can induce magnetism in iron, steel, nickel and cobalt because each atom of these metals is a little magnet. These atom magnets are random until a larger magnet induces them to all face the same direction so that their magnetic fields work together.

No matter how many other objects a magnet magnetizes, it is still just as strong.

A magnet can induce magnetism in iron or steel by stroking the metal in one direction many times with one pole of the magnet. The atoms in the induced magnet can be knocked out of alignment again by heat, dropping on the ground or hitting it with a hammer.

Magnet

Steel Needle or Iron Nail

Paper clip

Hammer

Rub one end or one side of your magnet along a needle or nail starting from the head to the sharp end. Do this twenty times. Touch a paper clip with the end of your needle to see if it is magnetized.

Bang the needle or nail with a hammer or drop it on the hard ground. See if it is still a magnet.

Electricity is dangerous to living creatures. Nerves tell muscles to flex with electric signals. Electric current could flow across the heart and stop it. Never use more than a battery (the highest being the 6.0 Volt flashlight batteries) to power your circuits. After the battery is dead, do not even think of using the electric outlet for power. A wall outlet provides 120 Volts and could electrocute a person. The current that is fine for a lamp could stop your heart and kill you.

Electrons do not zip along the wire when a battery pushes them. They make slow progress because they bump into the atoms along the way. A single electron travels the short distance around a circuit to the other end of the battery in hours. Electric current can be visualized as a tube of balls pushed at one end. If there is room a ball may work its way to the other end. The pushed ball pushes the next ball and it passes along the force to the other balls. When a person is electrocuted it is not because electrons are pouring into his body. The electromotive force from the lightening or electrical outlet is exciting the electrons in his body and they are transmitting the electromotive force along to other atoms in his body.

A switch opens the circuit by breaking the path that current flows upon. The battery will drain quickly when the switch is closed but while it is open, no electricity flows through the wire. Electrons are pushed from the negative end of the battery and pulled toward the positive end of the battery, but only if there is an uninterrupted path between them. When the switch is closed the circuit is complete and the negative end of the battery can push the electrons in the wire toward the positive end of the battery.

Materials:

Cardboard

Paper fasteners (2)

Paper Clip (1)

Punch two holes in the cardboard the length of the paper clip apart. Bend the smaller loop of the paper clip down and put the small side down on the cardboard. Fasten the end down with the paper fastener through one of the punched holes. Put the other paper fastener in the other hole. The large loop of the paper clip should stay up and contact the second paper fastener when pushed down. Wires attach to the paper fasteners to the circuit. The switch keeps the circuit open until the large loop of the paper clip is pushed down.

Attach one end of the wire wrapped around the nail to a paper fastener of the switch. Attach the other end of the wire to the battery with scotch tape. Attach another wire to the other side of the battery with tape and the other end to the second paper fastener of the switch.

Insert a piezoelectric bell or light emitting device (LED) between the battery and the switch. When the switch is closed the bell will sound or the LED will light up. The bell or light works if current flows through the device. This proves that current does not flow until the circuit has a complete uninterrupted path.

Electromagnets are useful because the magnetism can be turned on and off. Electromagnets lift and drop cars in junkyards. Electromagnets lift magnetic levitation trains that are extremely fast and energy efficient. Electromagnetic motors are used in electric appliances (refrigerators, washers, bread machines…etcetera). Superconductor laboratories that study matter use super-cooled electromagnets to push atomic particles around the accelerator.

Electric current is surrounded by a magnetic field. If the wire that carries the current is looped the magnetic fields are concentrated in the center (see wire coil below). An electromagnet is made by coiling coated wire around a piece of iron and running current through the wire. The iron becomes magnetized as the concentrated magnetic field from the wire coil induces the iron atoms to point their magnetic fields in the same direction. The strength of the electromagnet will depend upon the number of times the wire is wrapped around the iron and the voltage of the battery attached to the wires.

Wind a plastic coated wire around a large iron nail about 25 times. More windings cause the electromagnet to be stronger. Fit as many windings as you can on the nail and even wind a second layer if possible. Scrape the covering off each end of the wire.

Glue the foam to the cardboard. Stick the tip of the nail into it so that it is upright. Unwrap the large loop of a paper clip so that the short loop remains with a long wire down. Stick this paper clip into the foam so that the short loop is positioned closely above the nail. When the switch is closed the short loop will be attracted to the nail head and a tap will be heard. The paper clip should spring back and tap back each time the switch is closed. This may require some adjusting. Angle the paper clip stem back a bit so the foam can push it back.

Closing the switch will cause current to flow through the coated wire around the nail. The magnetic field associated with the current will be concentrated on the nail and will induce magnetism in the nail. The nail will attract the paper clip above it and a tap will be heard. The taps are controlled by opening and closing the switch.