Investigating magnetic field of a current loop prac questions help :/

[HarveyD]

hey guys

stuck on a few questions so any help would be appreciated ^^
1) Why would you not be able to use a compass on the North/South pole?
2) We aligned the frame so that the coil was lined up north/south and we got compass readings between North and East. So what would positions of the compass needle would be possible if the coil was instead placed with its place in an east-west direction...
3) Does anyone know what the relation between B and the current in the loops is? I have drawn a graph and it looks like a tan inverse..but that doesn't fit in with any formulae I've learnt

[Lasercookie]

1) Why would you not be able to use a compass on the North/South pole?

I've assumed magnetic north/south pole.
If you were on the pole, the compass would be attracted downwards. It would tilt down to the point that it would no longer be free to move left or right. (a decent, fancy compass would probably be able to work in this situation though) You could try experimenting with a bar magnet + compass.

3) Does anyone know what the relation between B and the current in the loops is? I have drawn a graph and it looks like a tan inverse..but that doesn't fit in with any formulae I've learnt

I'm pretty sure the only formulae on the course is F=ILB and F=qVB.

This might be what you're looking for (possibly): http://230nsc1.phy-astr.gsu.edu/hbase/magnetic/solenoid.html#c2

[HarveyD]

ah k, yeah i was thinking that, like the needle would move in all sorts of directions i think

hmm that formula actually fits in with the info, thanks for that