EE: How to heat a magnet with a wire while levitating a superconductor?

[SBrownJC]

Hi I'm doing my extended essay (like a research paper) for the IB and I'm having a bit of trouble with my setup and data process. The plan for my experiment goes something like this: I have a magnet wrapped in wire strapped to a battery and a superconductor in liquid nitrogen. After levitating the superconductor on the magnet, I'll record how much weight the superconductor can hold. I'll repeat this process for different temperatures of the magnet by heating up the wire.

1. Would copper wire be the easiest to use?
2. Would wrapping the wire on the sides of the magnet allow it to heat up the quickest or is there a different way to cover the magnet?
3. Also, do I put enough weights until the distance between the superconductor and magnet is half a cm or something? or until the superconductor can't levitate anymore?

 

[berkeman]

Can you post a diagram of your setup? (use "Attach files" below the Edit window)

Also, if you are using current through the wire wrapped around your permanent magnet to heat it, how do you avoid changing the net magnetic field, and how to you avoid demagnetizing the magnet?

 

[kuruman]

Hi I'm doing my extended essay (like a research paper) for the IB and I'm having a bit of trouble with my setup and data process. The plan for my experiment goes something like this: I have a magnet wrapped in wire strapped to a battery and a superconductor in liquid nitrogen. After levitating the superconductor on the magnet, I'll record how much weight the superconductor can hold. I'll repeat this process for different temperatures of the magnet by heating up the wire.

How can you do this if the superconductor is in liquid nitrogen? If it is isn't, it will not remain a superconductor long enough to take measurements.

 

[hutchphd]

I do not understand the purpose of the experiment. What is the hypothesis or relationship you are examining? Why is temperature of the magnet the independent variable?

 

[SBrownJC]

Can you post a diagram of your setup? (use "Attach files" below the Edit window)

Also, if you are using current through the wire wrapped around your permanent magnet to heat it, how do you avoid changing the net magnetic field, and how to you avoid demagnetizing the magnet?

I'm going to avoid demagnetizing the magnet by not heating the temperature up to 80 degrees or so. I'm probably going to heat it up until 50 or 60 degrees in increments of 10.

If I'm trying to determine how temperature affects the magnet which in turn affects how well the superconductor can levitate, then wouldn't changing the magnetic field be necessary to change the strength of the magnet?
Also if that's not the case and I should keep the net magnetic field constant, can't I use a wire made of a metal that doesn't affect it as much?

I haven't started the actual experiment yet so I don't have my setup.

 

[SBrownJC]

I do not understand the purpose of the experiment. What is the hypothesis or relationship you are examining? Why is temperature of the magnet the independent variable?

I'm trying to determine how changing the temperature of the magnet in my setup would affect how much force it can levitate the superconductor

 

[berkeman]

I'm going to avoid demagnetizing the magnet by not heating the temperature up to 80 degrees or so. I'm probably going to heat it up until 50 or 60 degrees in increments of 10.

That's not what I meant. I meant that running a current in a coil wrapped around a magnet will either add to or subtract from the overall B-field while the current is flowing. Also, if the current runs in the direction to generate an opposing B-field, that will tend to demagnetize the magnet over time and over cycles of the apparatus. You don't want that affecting your experiment, IMO.

I'm trying to determine how changing the temperature of the magnet in my setup would affect how much force it can levitate the superconductor

Why do you need a superconductor involved at all? If you want to understand how the strength of a permanent magnet varies with temperature, you can just use a small oven and a spring balance, no?

 

[berkeman]

BTW, there are ways to wind coils so that current in the coil does not generate a net magnetic field. Do some searching to see if you can find how that is done...

 

[kuruman]

I echo @berkeman's question, "why do you need a superconductor? I see a serious problem with temperature control. You will be trying to heat the magnet while the boiling nitrogen will be cooling the magnet.

A simpler setup would be to take two cylindrical magnets, place one on top of the other inside a plastic tube of appropriate diameter in repulsion. Then heat the bottom magnet from underneath (a hot plate might do it) and measure the separation between magnets.

 

[Steve4Physics]

To @SBrownJC: a few more things for you to think about...

How are you going to measure the temperature of the magnet?

Will the magnet have a uniform temperature? E.g. how will you know if the temperature inside the magnet is the same as its surface temperature?

Have you discussed any of this with your supervisor yet? Are they OK with it? Are they OK with you using liquid nitrogen?

I have supervised a few IB Physics EEs in my time (though some time ago!). I wouldn't be very happy with what you are proposing for reasons hinted at in this and other posts.

Please discuss your plans with your supervisor!

 

[DaveE]

Levitating a superconductor seems like an odd way of measuring the temperature dependence of a magnet's B field. You can do the same thing, I think, with a piece of iron (not superconducting). How about substituting a Hall-effect sensor for the superconductor?

OTOH, if you want to measure the effect of B-field strength on levitating superconductors, then how about an electromagnet which is really easy to control.

This sounds like an unnecessarily complex combination of two separate experiments to me. Step #1: what is the research question that you are really trying to address here? Design the simplest experiment to answer that question.

 

[SBrownJC]

Hi I'm doing my extended essay (like a research paper) for the IB and I'm having a bit of trouble with my setup and data process. The plan for my experiment goes something like this: I have a magnet wrapped in wire strapped to a battery and a superconductor in liquid nitrogen. After levitating the superconductor on the magnet, I'll record how much weight the superconductor can hold. I'll repeat this process for different temperatures of the magnet by heating up the wire.

1. Would copper wire be the easiest to use?
2. Would wrapping the wire on the sides of the magnet allow it to heat up the quickest or is there a different way to cover the magnet?
3. Also, do I put enough weights until the distance between the superconductor and magnet is half a cm or something? or until the superconductor can't levitate anymore?

The purpose and thought process behind my EE was to focus on maglev trains and how they float exactly. By recreating the setup of a cooled superconductor on a magnet, I wanted to determine how varying temperatures inside the engine would affect how well they levitate.
I'm using liquid nitrogen rather than helium because its more accessible where I live and I'm using permanent magnets rather than electromagnets because I'm not planning to make my superconductor move.
Please let me know if there's anything I should change.

 

[SBrownJC]

That's not what I meant. I meant that running a current in a coil wrapped around a magnet will either add to or subtract from the overall B-field while the current is flowing. Also, if the current runs in the direction to generate an opposing B-field, that will tend to demagnetize the magnet over time and over cycles of the apparatus. You don't want that affecting your experiment, IMO.Why do you need a superconductor involved at all? If you want to understand how the strength of a permanent magnet varies with temperature, you can just use a small oven and a spring balance, no?

If a coil might change the net magnetic field, would a hot plate or boiling water under the magnet work?

 

[hutchphd]

Also the Curie temperature of the very high field N52 magnet is surprisingly (to me) low...below boiling water Temp. So you would need to be careful not to overheat a subsection of the magnet.
You need to simplify and clarify your intent for the experiment.

 

[mfb]

How can you do this if the superconductor is in liquid nitrogen? If it is isn't, it will not remain a superconductor long enough to take measurements.

A cold superconductor quickly gets a layer of ice in air, which can keep it cold enough for quite some time.

@SBrownJC: I would heat the magnet first and then add the superconductor. If you can then place the magnet in a water bath until you are confident it has the same temperature throughout its volume, then quickly place it into the test setup (or drain the water). Heating with wires is more complicated, but you can try to keep its surface temperature constant.
I'm not sure why you want to combine temperature of the permanent magnet and superconductors, however. You can study the magnetic field as function of temperature without a superconductor, and then the interaction between a magnet and the superconductor in a separate experiment.