Physics teachers- a biologist needs you..

[Cathpot]

Just posted the following on the TES website, but it seems to move very slowly so am turning to the instant gratification that is mumsnet so I can get on and plan some lessons...

I am a biologist originally but teach all 3 sciences to KS4. Am about to teach electricity generation to Year 7. I am happy with the fact that if you move a wire through a magnet field electrons in the wire start to move, but I suddenly realised I have never actually understood why this is. When I look it up on line I get lots of websites that state what faraday's law of induction says, but no simple explanation of WHY an electron being exposed to a changing magnetic field decides to move. Can someone explain in simple terms what is going on from an electron point of view? Thanks

Electromagnetism is a force (like gravity). It's what makes electrons and other electrically charged particles interact with each other.

Electricity and magnetism are linked as a result - so electric fields produce magnetic fields and vice versa. You can't have one without the other.

So the magnetic field exerts force on the electrons in the wire - a bit like gravity exerts a force, making things fall.

I'm not a teacher - I did physics at uni. But not sure that was very clear!!

Hi iggly- actually very clear, and thankyou for taking the time to answer. It has made me think through what I know about electromagnetism and what I was really asking- I suppose its no more odd than iron filings responding to a magnetic field and I have never questioned the WHY there either.
In class no pupil has ever asked me why it happens in all the time I have taught it, nor has anyone ever questioned the WHY in other forces like gravity either. I suppose at the level I teach sometimes 'because it does is' all we've got.

This is why I prefer biology and chemistry as there do seem to be more 'this happens BECAUSE this happens' answers- unless of course you dig too deeply I suppose, atomically its all physics in the end!

Have got lesson sorted anyway- off to de-geek with bad tv and last of chocolate. Thanks again

I know what you mean. I did all three sciences. Physics is so fundamental and theoretical, it hurts your head after a while! But I enjoyed doing it, especially alongside philosophy of science.... Now that is geeky

enjoy the choc and tv!

ah..out-geeked, splendid!

Need to consider the repulsion of like charges that cause the electrons to move.

Dideinsteinsmum- can you explain for me?

If you take two magnets, the north poles will repel each other as will the south poles. However, the north pole of one magnet will attract the south pole of the other.

In the same way, like charges repel. So two electrons will repel each other as they both have negative charges.

In electronics we often talk about "holes" moving. That's because by convention electric current flows from positive to negative. However, what is really happening is that electrons are flowing from negative to positive. So we have the concept of a hole (the lack of an electron) which flows from positive to negative.

As for electromagnetism, "because it does" is about all we've got no matter how advanced you get. It is one of the four fundamental forces which means it cannot be described in terms of other forces. If you want to get into quantum mechanics you can describe it using perturbation theory as being mediated by the exchange of gauge bosons between particles. I'm not going to try and explain that - I don't understand it either!

HI prh47- yes am ok with like forces repel -just slight panic then that it was connected to electromagnetism in some way I hadnt thought of. In fact thats another thing no child has ever asked me- we teach them like charges repel and then later on that the nucleus is stuffed with positive particles and no one has ever asked how that is possible. I know now as I looked it up, but again its a problem of teaching outside my subject- I can spoon feed them GCSE physics but I can't enthuse or expand or wander off into related topics like I can for biology. Definately a shortage of physicists in the classroom- our department is small and all biol and chemists and I dont think thats unusual.