Fleming's left hand motor rule. Watch

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fishpaste
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I don't get it :|

Could somebody explain it to me? Do your fingers always stay the same? Which finger goes where? How do you work out which way current should be flowing?
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JSM
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(Original post by fishpaste)
I don't get it :|

Could somebody explain it to me? Do your fingers always stay the same? Which finger goes where? How do you work out which way current should be flowing?
left hand, fingers always stays the same - i cant remeber which finger is which
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username9816
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(Original post by fishpaste)
I don't get it :|

Could somebody explain it to me? Do your fingers always stay the same? Which finger goes where? How do you work out which way current should be flowing?
they scrapped it from the syllabus because it was crap.
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fishpaste
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Oh and this is with respect to particles going through magnetic fields.
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capslock
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(Original post by fishpaste)
I don't get it :|

Could somebody explain it to me? Do your fingers always stay the same? Which finger goes where? How do you work out which way current should be flowing?
When a wire carrying an electric current is moved in a magnetic field of a magnet the magnetic field induced by the wire reacts with the magnetic field of the magnet causing the wire to move outwards. Fleming's left hand rule helps you to predict the movement.

First finger - direction of magnetic field (N-S)
SeCond finger - direction of current (positive to negative)
ThuMb - movements of the wire

Hope this helps.
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fishpaste
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(Original post by bono)
they scrapped it from the syllabus because it was crap.
It's on my AQA syllabus, for working out the direction of a magnetic field in the experiment which discovered the specific charge of an electron (forgot the name).
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fishpaste
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(Original post by capslock)
When a wire carrying an electric current is moved in a magnetic field of a magnet the magnetic field induced by the wire reacts with the magnetic field of the magnet causing the wire to move outwards. Fleming's left hand rule helps you to predict the movement.

First finger - direction of magnetic field (N-S)
SeCond finger - direction of current (positive to negative)
ThuMb - movements of the wire

Hope this helps.
This is brilliant, but could you possibly explain how this adapts for an electron moving in a magnetic field?
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boygenious
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(Original post by fishpaste)
It's on my AQA syllabus, for working out the direction of a magnetic field in the experiment which discovered the specific charge of an electron (forgot the name).
Milikan's experiment. ahh a wonderful experiment indeed
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fishpaste
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Oh god this is going to sound so incredibly bad for an alevel physics student, what's the current?
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Nylex
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(Original post by fishpaste)
Oh god this is going to sound so incredibly bad for an alevel physics student, what's the current?
Your electrons moving in the field (as current is the rate of flow of charge, ie. electrons). When you use the left-hand rule, you're using coventional current flow though (positive to negative), rather than the direction the electrons are travelling in, which obviously will be opposite.
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fishpaste
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That's absolutely fantastic, thank you so much.

So to clarify, if the electrons were moving from left to right, and they accelerate downwards, then the magnetic field would be going into the page and would be represented by a circle with an x in. If they were accelerating upwards, the magnetic field would be coming out of the page, and would be representing by a circle.

And for an electric field, the direction of the field is the direction in which a positively charged particle would accelerate?
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boygenious
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(Original post by fishpaste)
That's absolutely fantastic, thank you so much.

So to clarify, if the electrons were moving from left to right, and they accelerate downwards, then the magnetic field would be going into the page and would be represented by a circle with an x in. If they were accelerating upwards, the magnetic field would be coming out of the page, and would be representing by a circle.

And for an electric field, the direction of the field is the direction in which a positively charged particle would accelerate?
yeh all 3 points are correct
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fishpaste
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Once again, cheers.

I'm all set. But if anybody feels like answering another questoin, how would you answer the question "explain what is meant by a stationary wave." [4 marks]?
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hornblower
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It's always rather amusing in physics exams to see people with both their hands doing Fleming's LHR and RHR actions at the same time. It looks like they are playing with imaginary guns!

J.
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elpaw
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if you've done further maths, you can always remeber that
F = q v x B
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m 69 d
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and don't forget his right hand rule!
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glance
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(Original post by m 69 d)
and don't forget his right hand rule!
:eek: Is your display name really true?! :eek:
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m 69 d
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(Original post by elpaw)
if you've done further maths, you can always remeber that
F = q v x B
How does doing further maths get you that
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planetzod
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Forget the stupid hand rules and just remember which way stuff goes.

That's what I do anyway
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material breach
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(Original post by m 69 d)
How does doing further maths get you that
cos the bold letters are vectors and its a cross product and this thread is ancient
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