Name __________________________________________ Date



Name __________________________________________ Date __________________

Study Guide – Magnets and Electricity

Magnets attract materials that are made from iron. Each end of a magnet has polar attractions. This polarity is identified as either north or south. If you cut a magnet in half, each half will have a north and south end, just like the original whole magnet. Magnets exhibit the strongest pull at each end, or pole. Just as with electrical charges, like poles repel (north repels north, and south repels south). Opposite magnetic poles attract (south attracts north). Our earliest magnets were made of natural magnetite, which was also called lodestone.

Magnets are used in many things. For instance, magnets are used in compasses to indicate direction. The Chinese were the first to use magnets in compasses. A free-swinging magnet’s “north pole” is actually a south pole, and will point towards the north because opposites attract. The “south pole” on a solid magnet is actually a north end and will be attracted to the actual South Pole.

Magnetic fields surround earth, and meet at the North and South Poles. These poles do not exactly match the Earth’s axis. One way to determine a magnet’s strength is by how much iron-based metal it can pick up.

Electromagnets use electricity to create a magnetic field. Electromagnets are used in all kinds of motors. Electromagnets are temporary magnets. Permanent magnets are used in other ways, but may also be used in motors along with electromagnets. Electromagnets can be made stronger by wrapping more loops of wire around the core. A motor is a device that uses current to produce motion. The ends of electromagnets, that are useful, are also called poles.

Magnets and electrical charges are alike because they are both surrounded by an area where forces act.

Many famous scientists helped us understand electricity and magnets. In 1752 Benjamin Franklin observed sparks along a kite string, attracted to a key at the end of his kite during a thunderstorm. Franklin tried many experiments with electricity. Michael Faraday built a generator and a transformer using electromagnets in 1830. These were the basis of our modern motors. Thomas Edison patented the first light bulbs, and improved Alexander Graham Bell’s telephone among many other inventions that he created. Today, mag-lev trains use magnets to lift trains slightly above tracks and push them forward with magnetic force. No wheels are used. Research on these continue in Japan. And in medicine, Dr. Damadian invented the MRI – a Magnetic Resonance Imaging machine which gives us a better view than X-rays, in hospitals. This machine uses magnets.

1) What material is attracted by magnets? _________________________

2) Where are the poles on a magnet located? _________________________

3) What happens if you cut a magnet in half? ________________________________________________________________________________________________________________________________

4) Are magnets strongest in the middle, or at the ends? ______________________

5) Opposite magnet poles attract or repel? ________________________________

6) What tool uses magnets to indicate directions? __________________________

7) If a magnet is hung from a string, which direction will the north-seeking pole of the magnet point? _____________________________________

8) List three objects that a magnet will stick to in the classroom.

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9) Name two objects that use electromagnets in their motors.

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10) Name two of the four scientists famous for their experiments with magnets or electricity.

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Bonus:

How does a Mag-Lev train work?

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Science Quiz (continued)

11) Name two objects that use electromagnets in their motors.

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12) Name two of the four scientists famous for their experiments with magnets or electricity.

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Bonus:

How does a Mag-Lev train work?

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