# Magnetic Tightrope

moas magnetic1a.png
How a magnet affects another magnet and a compass

Magnets: Demonstrating force at a distance

Sunshine State Standards: SC.B.1.2 SC.B.2.2

Materials:

• Bar Magnets
• Circular Magnet
• Compass
• Steel Nail
• Aluminum Nail
• Short Dowel

Demonstration Item: Magnetic Pendulum Set

To Know:

• Magnets have a North Pole and a South Pole, although they may have different shapes.
• Similar poles (North-North) repel each other at a distance.
• Opposite poles (North-South) attract each other.
• These forces can be noticed at a distance and get stronger as they get closer.

To Do and Notice:
A compass is a very small magnet that is affected by the earth’s natural magnetic field.

• If the compass is not near a magnet it will point to the North Pole.
Which way is the North Pole at this table?

moas magnetic1b.png

• Place the bar magnet on the table and move it closer to the compass.
What happens? Why?
• Try to push two bar magnets together North to North.
What happens?
What happens if you move an “S” end close to an “N” end?
• Try to move a bar magnet close to the circular magnet.
What happens?
• Try to switch the ends of the bar magnet? What happens?
Where is the North pole and the South pole on the circular magnet?
Can this be verified by putting two magnets on the small round rod?
• Put a single bar magnet in the middle of the table. Place all of the compasses around it.
What happens to the needles?
Which directions do they point?

Some materials are attracted to a magnet (magnetic) and some are not (non-magnetic).

• Try putting the magnet close to the two nails.
What do you think the two different kinds of nails are made of?

What’s Happening?

• Compass needles line up with magnetic fields. Since the earth is a magnet, a compass will normally line up with the earth’s magnetic field. Because opposite magnetic poles attract, the North point (pole) of the compass is attracted towards the magnetic South pole of the Earth.
• Did you know that the magnetic South Pole is located in the very far northern part of Canada and the magnetic North pole is located in the Antarctica near the geographic South pole of the Earth.
• Since the bar magnet is close to the compass, its magnetic field is stronger that the Earth’s field and will attract the compass needle as it gets closer. You can feel this force and how it varies with distance when you try to push the two North poles (or South poles) of the bar magnets together.
• The bar magnets are magnetized in the direction of the bar as marked with an “S” or “N”. The circular magnets are magnetized such that it forms a ring magnet with the North Pole on one side of the ring (flat side) and the South Pole on the other side of the ring. Your experiments with the bar magnets show you which side is North and which side is South. You can see this because of the attraction or repelling force of the “N” or “S” end of the bar magnet as you approach the sides of the circular magnet. When you put the rings on the dowels they either stick together because you have a north side facing a south side, or one of the rings will float on the magnetic forces because you have a North to North or a South to South sides of the ring together on the dowel.
• The force fields of a magnetic flow from one pole to the other can be visualized by arranging the compasses. You can observe these fields by observing the pattern of compass needles and observing how they line up. The needles line up with the direction of the magnetic force field that curves around from one end of the bar to the other. If you put two bar magnets a foot apart on the table you can observe different force fields between the two magnets.