Wednesday, 12 June 2013

Science: How strong is a magnet?

Honi has really enjoyed playing around with magnets for the last few days.  She has learnt so much about them so bit by bit I will share with you all the experiments and projects we've been doing.
We wanted to test how strong our magnets were so this is how we did it...

First you can write out a simple table, or do as we did and write down notes to record our hypothesis and our findings.  We first wrote down Honi's hypothesis of how many centimetres away the magnet would be to be able to attract a nail from and the same for a pin.  Honi wanted to see if there was a difference between a standard magnet and a rare earth magnet so we included that too.  This is what Honi's page looked like at the end:
Honi wasn't much into writing that day so she got me to scribble it down for her.
We put a ruler on the table and slowly, bit by bit moved the magnet closer and closer until the nail was attracted then noted how many cm away it was when this happened.
We did the same again for the pin and repeated this process again with a rare earth magnet.

Next we wanted to see if it made any difference if we did it vertically, thinking that gravity might affect the results.  To do this we stuck the ruler to a wall and did the same thing.

We also tested a magnet's strength by seeing how many paperclips it could hold like this...

Of course we hypothesised first Honi thought it would be 10...  I won't tell you the results, I'll let you have a go and figure it out for yourselves!

Naomi asked me today: why is a rare earth magnet called a rare earth magnet?  A good question as I was unsure of the answer myself.  I couldn't find out why but I did find lots of information about what they are...
This is an extract from: Wikipedia
Rare-earth magnets are strong permanent magnets made from alloys of rare earth elements. Developed in the 1970s and 80s, rare-earth magnets are the strongest type of permanent magnets made, producing significantly stronger magnetic fields than other types such as ferrite or alnico magnets. The magnetic field typically produced by rare-earth magnets can be in excess of 1.4 teslas, whereas ferrite or ceramic magnets typically exhibit fields of 0.5 to 1 tesla. There are two types: neodymium magnets and samarium-cobalt magnets. Rare earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking and chipping.
If you are interested in how they are made click this link here.

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