# Want to set up a constant magnetic field to do experiments under

1. Dec 26, 2012

### lostminty

Hiya,

So I want to do some experiments with concrete curing under a magnetic field.

The samples would need to be approximately a 2" diameter tube maybe 8" long.

I'm not that aware of how a magnetic field would behave any more, been awhile since I did any physics outside of classical mechanics.

any way..

was thinking I could essentially make a coil magnet like this:

having the concrete setting within the coil?

2. Dec 26, 2012

### Simon Bridge

That's what I'd try ... you'd basically be wrapping wire around whatever the concrete is sitting in and hooking it to a power source.

3. Dec 29, 2012

### Mike_In_Plano

Evan, fairly low strength fields can be developed with a Helmholtz coil. You can find details under Wikipedia.

4. Dec 29, 2012

### lostminty

thanks :)

5. Dec 31, 2012

### Enthalpy

Helmholtz, sure... BUT what induction is needed? With an air coil and a pair of watt you get 1mT. For 1T (provided 1T has any effect on concrete...) it needs other means, especially an iron core and the proper design around it, and for >2T you've lost because the iron core doesn't help.

6. Jan 8, 2013

### lostminty

The concrete will be made with iron sand. Maybe that will provide something analogous to an iron core.

I was thinking of using a computer power supply, on the 12V rail.

Bit confused as what to do about the amp load. The power supply has maybe 15A? on that rail.

I have some 0.63mm enamel coated copper wire, not sure how much of it I have..rough calculation of two 8m lengths. This will provide about 0.8 ohms of resistance.

If I were to hook that straight up, thats 15A right there, pushing it really.

Would I add a resistor to that to cut down the current?

7. Jan 8, 2013

### I_am_learning

How long do you need to hold the field?
The design of electromagnet is mostly about how much current you can pass through the wires without melting them down.

8. Jan 8, 2013

### Enthalpy

Again, what induction? Most electromagnetic designs are impossible, yours seem to belong to this category.

9. Jan 8, 2013

### lostminty

I..don't really understand.

I want the titanomagnetite particles to align to the field...hopefully creating directional microstructure

It wouldn't need to be too long, will have to do some viscosity calculations to see how long it will take