Tuesday, 10 May 2011

Magnetic Mischief

Today we had a look at magnets.  

We first made two lists of items attracted to the magnet and not attracted to the magnet. Along with the expected, such as a steel bar is and a pencil isn't, Benedict hit on the surprise that a pair of scissors did and didn't; they had a plastic handle and steel ends!  After trying two bar magnets together, we then considered the principal that like poles attract and opposites repel.


Dad's machining of cast iron on the lathe has produced a useful waste product, as the carefully collected iron chips proved to be quite acceptable as iron filings (chips from lathe work are actually larger than true products of filing).

We tried a bar magnet under a piece of paper with iron 
filings and saw patterns of the magnetic force fields

We then tested the effect of various magnets under the paper, a book and the table, to see the various effects.



Under that table, the bar magnet and the 
stronger horseshoe magnet had no effect at all


So we tried the heavy duty magnetic base from Dad's workshop


And from under the table, this had a definite effect!



Then we tried the effects of thick and thin glass





After that, we moved onto referred magnetism, using paper clips as the extending media

 the bar magnet lifts a chain of 3 paperclips...

the horseshoe magnet lifts a chain of 4 paperclips...
 ...but oddly, the magnetic base does no better, with only 4 paperclips.
Considering the range of magnets, we slid each magnet over a centimetric graph paper until it was able to attract paper clips which had were on the baseline.

The range of the bar magnet was 2cm

But the range of the horseshoe magnet was only just over 1cm


 The range of the magnetic base was the greatest at 5cm







Finally, we made a compass.  We magnetised a darning needle by stroking the strongest magnet along it.  The needle was then suspended from a piece of wool in a glass.
The needle had a tendency to align itself along a North-South axis.  When the glass was rotated, the needle tried to orientate itself again, however, the resistance presented by the suspension thread meant that a N-S orientation could not be obtained when the glass was rotated far.


The logical correction of this fault would be to have the needle on a cork, floating in a dish of water, but time ran out.




A productive work outcome!

After lunch it was Mum's turn to pitch in and Benedict worked on a cryptogram quiz for his spellings:


This was then followed by two pages of quick drill mathematics followed by another book from his reading pile:

Whilst Benedict and Pip were engaged in another craft activity, I took the chance to sneak into the garden and photograph my most favourite spot:

All credit to Sara for all her hard work in painting and thoroughly cleaning the greenhouse from top to bottom!

View from the greenhouse door.

Blooming flowers waiting to be planted!


A better view of my favourite spot!


Our twinkly, twirly bird scarers/sun catchers dancing in the breeze.

Whilst I was hanging the last of these colourful discs I was greeted with the presence of an unusual visitor in the garden:


My very own Indian brave and little sister squaw could be found here:


She's even sitting crossed legged too!!

As I type we are just about to embark on a craft activity present for one very special Nanna, who has a birthday on Thursday.


1 comment:

  1. What a great unit study! Benedict looks so engrossed.

    ReplyDelete

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