A current-carrying conductor in a magnetic field experiences a force

ozymandias1 — Mon, 17 Nov 2008 21:58:35 +0000

Two applications; one practical, one not so practical.

The mystery of magnetism

ozymandias1 — Fri, 01 Aug 2008 18:37:49 +0000

: Floating rings used to demonstrate magnetic repulsion

Sometimes the most basic question can be the hardest to answer. “How do magnets work?” is one such question. If you’re a teacher like me you’ll probably end up using fancy terms like “North and South Poles” and “Opposite Poles Attract”, and may even go on to demonstrate it using the floating magnets above.

Or if it’s a senior class you might talk about the material having “Magnetic Domains” which are usually randomly oriently but in a magnet are all lined up parallel.

And this invaribly works.

But there’s usually one student (quite often it’s someone who is not great academically, and consequently may remain in the background for much of the time) who’s not happy with this.

But how does one magnet know that the other magnet is there?

And that, my friends, is a great moment. It means that at least one person in my class managed to avoid all the ’education’ that I stuff down their throats, and maintained his ability to think for himself. ‘Course that won’t help him (or her) much when it comes to exam time, but at least in my mind it counts for a lot.

A former student once sent me a card on which he wrote “Thanks sir, I was in your class for two years and in that time I learnt nothing”. It was one of the nicer compliments I have received. Cheers Luke.

I hope to be teaching more Junior Cert Science this year and need to remember to avoid the temptation of throwing in jargon as a substitute for deeper explanations. For that matter, when the apple falls from the tree how does it ‘know’ which way is down?

Or here’s one for leaving cert students: why is the charge of a proton (which is composed of three quarks) the same as the charge of an electron if they are completely seperate particles?

Here’s a lovely article taken from the science magazine Discover detailing how the author realises that nobody actually understands how magnetism works.

As teachers, we need to become comfortable discussing the limitations of what we know.

Think for Yourself » Magnetism

A current-carrying conductor in a magnetic field experiences a force

The mystery of magnetism