Generating electromagnetic fields with an electromagnet

[Rydyn]

Hello,

I am working on a science project to generate electromagnetic fields. From what I understand, the simplest way to do that is to coil copper wire around an iron core. My initial goal is to create a magnetic field with a maximum strength of 500 microtesla. Can this be accomplished if I have a maximum input current of 50 mA, or do I need a higher input current? The other parameters that I wish to use are a radius of no more than 8 cm and a length of no more than 3 cm.

Thank you for any help you can provide!

 

[jim hardy]

Have you seen this calculation before ?
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/solenoid.html

 

[Rydyn]

Thank you, that helps a lot. I guess my next question is about the windings. Given my other specifications, I will need a high turn density. Is there a maximum turn density that can be used?

 

[anorlunda]

I will need a high turn density.

What makes you say that? From that calculator that @jim hardy linked:

That is 0.1/0.000500 or 200 times more than your requirement.

 

[jim hardy]

I will need a high turn density.

Always check your intuition against the math.
Otherwise your intuition never gets any better.

 

[Rydyn]

Ok I think I am getting it now. One last question. The equation gives the strength at the center of the solenoid. Does that mean at the end of the solenoid at the center of the radius(r=0)? From that point, the field strength decreases by z^2 away from the solenoid when r is held at 0, right?

 

[jim hardy]

Does that mean at the end of the solenoid at the center of the radius(r=0)? From that point, the field strength decreases by z^2 away from the solenoid when r is held at 0, right?

You're asking about the behavior near the end?

To achieve precision is a complicated calculation
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980227402.pdf
you might calculate a few points using that NASA note and try a east squares fit on them
...
.and i don't pretend to have ever done it

old jim

 

[gneill]

Do a web search on "magnetic field on the axis of a solenoid". This hit may help:

http://www.phys.uri.edu/gerhard/PHY204/tsl215.pdf