Help.... Lenz's Law and Eddy Currents (1 Viewer)

[Marianna]

Does anyone know of any good notes or has a good explanation of Lenz's Law and its connection to the conservation of energy and the eddy currents.
I understand all of Faradays experimentations etc but I don't get this bit...
I get the whole electromagnetic breaking stuff and the electromagnetic heating a possible form of cooking....

But don't get Lenz's Law and how it ties in...

help....

 

[freestyler__54]

jacaranda, or try howstuffworks.

this is how it works...

1. the magnetic field moves and it doesnt like that (cause this lenz dude says so)
2.so it tries to make a magnetic field where there was one before
3. use flemings rule (FBI) or right hand palm to work out the rest

 

[Morgues]

Conservation of energy occurs because it opposes the creation of more current by inducing the current in such a direction that the created magnetic field opposes the original magnetic field

If the created magnetic field didnt oppose the motion but acted the other way then more current would be created even if there wasn't anymore relative motion between the flux and the conductor

This would defy the law of conservation of energy, in this case current can't be created without work being done

Just BS something like that in the test and you will get the marks

 

[Minai]

yep
and make sure u kno its applications(the ones Bon mentioned), as well as wat it is

 

[Marianna]

THANKS!

Thanks sooo much guys!!

I'm getting a bit worries about the cssa physics trial tomorrow... I though I was prepared but the more I read the more I realise there is so much more I should know....

not happy jan....

 

[Morgues]

I know the general outline but once it comes to the small obscure details........ill be staring at the paper with a blank expression

Going through Jacaranda now there are so many little things that they can easily ask........anyway good luck everyone doing CSSA tomorrow

 

[Big Willy]

Has anyone mentioned Eddy Currents?

That concept is used on induction cookers - you can place ur hand on it and it wont burn you, you have to have a metal contact on the surface of the cooker.

Also, eddy currents are induced to oppose the current in the opposite direction - it provides a resistance, otherwise conservation of energy would be defied coz you'd be getting someting for nothing (ie you put some energy to get it going, and it stays like that (motors, induction cookers etc) forever)

And in motors, you have a laminated iron core (slits) to prevent eddy currents, and hence, reduce heat

 

[-=«MÄLÅÇhïtÊ»=-]

in simple english

if the magnetic field didn't opose, it'd suck the bar magnet into the coil. This creates kinetic energy. Due to conservation of eneergy, u cant create energy from nuffin.

 

[Minai]

Originally posted by Big Willy
Has anyone mentioned Eddy Currents?

That concept is used on induction cookers - you can place ur hand on it and it wont burn you, you have to have a metal contact on the surface of the cooker.

Also, eddy currents are induced to oppose the current in the opposite direction - it provides a resistance, otherwise conservation of energy would be defied coz you'd be getting someting for nothing (ie you put some energy to get it going, and it stays like that (motors, induction cookers etc) forever)

And in motors, you have a laminated iron core (slits) to prevent eddy currents, and hence, reduce heat

if u read above, ppl have already mentioned that