Magnetism Question

[Shark 774]

Ok, so this is from the 2007 synchrotron section, but only requires basic magnetism knowledge.

The answer is B: the electrons are deflected OUTWARDS, but I can't understand why, considering that the whole point of the injection magnet is to deflect the electrons inwards, as stated in the question.

Any ideas?

(see attached)

[Lasercookie]

I'm not sure of the answer, but here are my thoughts:

What's the direction of the field?

I think these might be wrong, but the direction of the electron (thumb) is to the right. The direction of the force (palm) is inwards. So that would mean the field would be vertically upwards/out of the page.

When the electrons come around for the second rotation, the field is still out of the page/vertically upwards. The direction of the force would depend on the direction they are travelling.

I don't know. Does something weird happen in synchrotrons, where they change from being negatively charged to positively charged? If that is the case, that would explain it. The direction would still be right (or whatever it's meant to be, looks like it's on an angle), but it would be deflected in the opposite direction due to the charge.

[Shark 774]

I'm not sure of the answer, but here are my thoughts:

What's the direction of the field?

I think these might be wrong, but the direction of the electron (thumb) is to the right. The direction of the force (palm) is inwards. So that would mean the field would be vertically upwards/out of the page.

When the electrons come around for the second rotation, the field is still out of the page/vertically upwards. The direction of the force would depend on the direction they are travelling.

I don't know. Does something weird happen in synchrotrons, where they change from being negatively charged to positively charged? If that is the case, that would explain it. The direction would still be right (or whatever it's meant to be, looks like it's on an angle), but it would be deflected in the opposite direction due to the charge.

Nope nothing weird like that happens (I don't think that's even possible ha ). The field would be INTO the page, not out. In using the right hand rule you used electron direction instead of current (they are opposite). So yeah I have no idea how the magnet would suddenly force it the opposite way to how it was before..... Hmmm. 

[Lasercookie]

Nope nothing weird like that happens (I don't think that's even possible ha ). The field would be INTO the page, not out. In using the right hand rule you used electron direction instead of current (they are opposite). So yeah I have no idea how the magnet would suddenly force it the opposite way to how it was before..... Hmmm. 

I always get confused about the electron direction stuff lol.

But yeah, there must be some explanation somewhere. The assessor's report or itute didn't seem to regard it as a dodgy question. If you want some reassurance, most of the state did very badly on this question.

[Shark 774]

Nope nothing weird like that happens (I don't think that's even possible ha ). The field would be INTO the page, not out. In using the right hand rule you used electron direction instead of current (they are opposite). So yeah I have no idea how the magnet would suddenly force it the opposite way to how it was before..... Hmmm. 

I always get confused about the electron direction stuff lol.

But yeah, there must be some explanation somewhere. The assessor's report or itute didn't seem to regard it as a dodgy question. If you want some reassurance, most of the state did very badly on this question.

Ha right, thanks. Hopefully I can sort out why their answer is correct. At this stage can't find anything on the net, and unfortunately this is one of the set-backs of doing a topic that your teacher doesn't teach (although I doubt he would even know anyway coz he sucks!)