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Magic Magnetic Fields
Have you ever wondered why magnets attract and repel each other with a seemingly invisible force that appears as if from nowhere when you place two magnets close to one another? Or why your paperclips always stick to your scissors in your pencil case? The answer lies with magnetic fields!
Magnetic fields are created by moving electric charges. Bar magnets, like the one seen here, have a permanent magnetic field surrounding them due to the special arrangements of the atoms inside the magnet.
Any charge placed in a magnetic field will feel a force, the magnetic force. This is the force that attracts or repels magnets from one another, and it is this force which moves the iron fillings in the familiar experiment shown above. They are tracing out the magnetic filed lines of the magnet.
Magnetic field lines help to represent the strength and direction of the magnetic field around a source. The closer together the lines, the stronger the force is at that point. The strength of the magnetic force decreases the further you go from the magnet.
The Earth has its own huge magnetic field, with magnetic field lines starting at the North Pole and finishing at the South (much like the ‘North and South’ poles of a magnet!)
The Earth has its own huge magnetic field, with magnetic field lines starting at the North Pole and finishing at the South (much like the ‘North and South’ poles of a magnet!)
For hundreds of years, before satellite navigation was even dreamed of, explorers have toured the globe with ease thanks to the incredibly clever yet simple device: the compass! A tiny magnet attached to the pivoting hand of a compass allows it to align with the Earth’s magnetic field so it will always point north.
Amazingly, many animals are able to sense the Earth’s magnetic field, using it as an ‘internal compass’. This is how birds know to fly south for the winter!
Some good web links to try:Education@NASA
http://www.creativekidsathome.com/science/magnet.html
http://www.kidskonnect.com/Electricity/Electricity.html
