Can I Use Magnets to Create a Temperature-Sensitive Pendulum?

[AlchemistK]

I have two quite powerful magnets that i took from a microwave magnetron.
Are there any interesting experiments or activities i could do with them? Maybe be costruct something?

 

[Lame One]

Something that I might try is to create a "perpetual" machine. Magnets become less magnetic when they are heated (but check to make sure that yours get it back! Some do NOT). If you set up a magnet on a pendulum, then, off to one side of the swing, put a candel. Then, set up another magnet above the candle, so that it is not being heated too much but is able to bring the first magnet to it. The hanging magnet will be pulled to the other one, but the candle underneath will heat it up, causing it to become less magnetic. It falls down, cools, and the cycle starts again.

 

[JaredJames]

Something that I might try is to create a "perpetual" machine. Magnets become less magnetic when they are heated (but check to make sure that yours get it back! Some do NOT). If you set up a magnet on a pendulum, then, off to one side of the swing, put a candel. Then, set up another magnet above the candle, so that it is not being heated too much but is able to bring the first magnet to it. The hanging magnet will be pulled to the other one, but the candle underneath will heat it up, causing it to become less magnetic. It falls down, cools, and the cycle starts again.

Perpetual motion discussion isn't allowed at PF.

The description of the device you have given won't work. Period.

 

[Lame One]

It is not perpetual motion, hence the quotes. It needs to be constantly fueled with a candle, which, of course, is a consistent input of energy.

 

[JaredJames]

It is not perpetual motion, hence the quotes. It needs to be constantly fueled with a candle, which, of course, is a consistent input of energy.

Perpetual motion does not imply free energy. That would be an over unity device.

Perpetual motion simply means it will keep going without stopping.

Regardless, the design of the system proposed will not work.

EDIT: I suppose I could be taking the definitions of the words too literally. In which case, quotes accepted.

 

[Kracatoan]

http://www.all-science-fair-project...4d9c356d0cabb2b7a8ee1e0eb46.html#curie_effect

is the experiment being referred to, the word perpetual is just using hyperbole for effect, to make the experiment sound more fun.

 

[sophiecentaur]

There is a similar 'perpetual motion' toy which consists of a bird made of blown glass. It dips its beak, repeatedly into a bowl of water without any apparent source of energy. The 'engine' works from the latent heat of vaporisation of the water on the bird's beak which condenses and evaporates some alcohol inside the bird and alters the balance. The room supplies the energy, ultimately.

 

[JaredJames]

But would the suspended magnet cool down enough in the short 'swing' time for this to be effective and actually work?

 

[Kracatoan]

Never tried it myself, but apparently it does.

 

[Dr Lots-o'watts]

You could do a magnetic pendulum, such as this:
http://www.bytelove.com/stuff/gadgets/romp/prod_95.html

 

[sophiecentaur]

But would the suspended magnet cool down enough in the short 'swing' time for this to be effective and actually work?

There would be many 'cooling' swings, once the Curie Point was reached and the main magnet let go. Only when the magnet cooled enough down would it be attracted back towards the main magnet.

 

[Lame One]

It would cool down enough, because, if you think about it, it only starts cooling the second it's too far away. Then, it is immediately pulled back up. Of course, correct placement is required.

 

[JaredJames]

There would be many 'cooling' swings, once the Curie Point was reached and the main magnet let go. Only when the magnet cooled enough down would it be attracted back towards the main magnet.

I'm not convinced, this is one I'd like to see in action.

EDIT: Job done -

Rather disappointing to be honest. Was hoping for more pendulum action.

 

[sophiecentaur]

I agree - a bit disappointing. It's all a bit light weight to be impressive.
It will all be a matter of time constants. If the swinging magnet is bigger (stronger and more massive), I think there will be more of a lag in the temperature changing and it will get a chance to swing further away before it goes below TCurie and gets pulled back.
I guess you need to have it suspended so that it is 'just' attracted to the big magnet when cold and the candle needs to be 'only just' powerful enough to heat it up. Then, once it's been let-go, it won't be pulled back until it's had time to cool down a lot.