Makes the earth like a huge horseshoe magnet.
Runs exactly through the geographic poles.
Makes a compass work
Makes an electromagnet work.
Are horizontal at the geomagnetic equator.
Are vertical at the geomagnetic equator.
Are never horizontal, no matter where you go.
Are perfectly symmetrical around the earth, even far out in space.
Can be either repulsive or attractive.
Is never repulsive.
Gets smaller as the magnet gets closer to the metal.
Depends on the geomagnetic field.
Motion of electric charge carriers.
The north geomagnetic pole.
In atoms of ferromagnetic materials.
At a north magnetic pole.
At points where the lines are straight.
In electric charge carriers.
Gets stronger with increasing distance from the wire.
Is strongest near the wire.
Does not vary in strength with distance from the wire.
Consists of straight lines parallel to the wire.
Overall magnetic field strength.
Magnetic flux density.
Charged particles stream out from the sun.
The earth’s magnetic field is affected.
Electrical power transmission is disrupted.
More than one of the above can occur.
Attracts only permanent magnets.
Attracts pure, unmagnetized iron.
Repels all permanent magnets.
Either attracts or repels permanent magnets, depending on the polarity.
An electromagnet can be switched on and off.
An electromagnet does not have specific polarity.
An electromagnet requires no power source.
Permanent magnets must always be cylindrical, but electromagnets can have any shape.
Can make a good ac electromagnet.
Repels both north and south magnetic poles.
Is always a diamagnetic material.
Is well suited to making a permanent magnet.
An ac relay.
A dc relay.
An armature coil.
A field coil.
Voice recording and playback.
Video recording and playback.
Digital data storage and retrieval.
All of the above.
A disk lasts longer.
Data can be stored and retrieved more quickly with disks than with tapes.
Disks look better.
Disks are less susceptible to magnetic fields.
A dc motor.
A tape recorder.