Electromagnets

A magnetic field is produced when an electric current flows through a coil of wire. This is the basis of the electromagnet. We can make an electromagnet stronger by doing these things:
wrapping the coil around an iron core
adding more turns to the coil
increasing the current flowing through the coil

The magnetic field around an electromagnet is just the same as the one around a bar magnet. It can, however, be reversed by turning the battery around. Unlike bar magnets, which are permanent magnets, the magnetism of electromagnets can be turned on and off just by closing or opening the switch.

the earths magnetic field

The Earth does not contain a giant bar magnet, but it behaves as if it does. The Earth has a magnetic pole in the north and one in the south. Compasses work because bar magnets can line up in the Earth's magnetic field and point north. Make sure you understand these things:
the north pole of a bar magnet is actually called the 'north-seeking pole', and it points to the Earth's magnetic pole in the northern hemisphere
the south pole of a bar magnet is actually called the 'south-seeking pole', and it points to the Earth's magnetic pole in the southern hemisphere. The magnetic pole near the geographical North Pole attracts a bar magnet's north pole because it is in fact a magnetic south pole. In geography and navigation it is always called the 'north magnetic pole' which can make things confusing.

Small compasses called plotting compasses can be used to show the magnetic field around a bar magnet, instead of using iron filings. The needle in each compass turns and lines up along the field lines.

f we arrange some plotting compasses around a bar magnet, we see that the needles point away from the magnet's north pole and towards its south pole.

homework:

REVISE FOR A BADGER ASSESMENT ON FRIDAY (i think) ABOUT MAGNETS AND ELECTROMAGNETS 8J
you can use the links below:
http://www.bbc.co.uk/schools/ks3bitesize/science/physics/magnetism_intro.shtml
http://www.sgfl.org.uk/berryhillscience/Year8/8J
http://www.google.co.uk/search?hl=en&rlz=1T4TSEA_en-GBGB273GB274&q=magnets+and+electromagnets+powerpoints&meta= ( go onto the 1st site)
you can cheak out some of the other sites on the site above


you can do some reasearch on some super search engines;

• www.google.com or www.google.co.uk
• www.ask.com
• www.dogpile.com
• www.yahoo.co.uk/

so you should cheak it out plus the techer didnt say the test is so you have to bear with it.

this is my blog for revison like school stuff and test stuff unfortunatly i just made this blog to make revision a little easier 4 me i'm a neek or anything just soo you know cos if you think i'm a neek then your a bitch.