Measure power of an electromagnet

[luiHS]

hello.
How could I know the magnetic power of an electromagnet?

I know the supply voltage, which is 50v, I can measure the consumption in Amps and the resistance of the coil, but what really interests me is the power of the magnetic field it generates.

It is a round electromagnet to hold metal objects.

[eugene]

By "power" do you mean the force that a magnet exerts on a nearby magnet or hunk of iron?

Besides building the thing and then measuring what you have, some predictions can be made with finite element analysis (FEA.) FEMM is free to download and is not too hard to learn. The downside of FEMM is that it can model only 2D systems, not 3D. But if there is enough symmetry to express your system in 2D, in either Cartesian or cylindrical coordinates, then it is not outside the realm of ordinary people like us to model.

[anda3243]

I have many time successfully designed a magnetic system using this free software.

https://www.femm.info/wiki/HomePage

It has some Windows95 vibes, but is easy to learn. I have successfully designed some special solenoids and had this SW present the force in N. For sure there is always some difference between simulation and reality, but it is a good start before committing to prototypes and real life tests.

Some magnet and hall-sensor plots I made recently

[Doctorandus_P]

You can buy simple ceramic or other permanent magnets, and these do not need electricity to work.

In any electromagnet all consumed power (exept for the initial switch-on) is converted to heat by the ohmic resistance of the wire used.

It roughly means that if you double the wire diameter (quadruple circumverence) and then als use 4 times as many windings, the total resistance, and therefore the power consumption of the magnet stays the same, while the magnet is 16x bigger and the generated magnetic field is 4x stronger.

Holding force is also influenced a great deal by any gap between the electromagnet and whatever it is holding. Even a 0.1mm gap has a dramatic effect.

[TimFox]

If you have a fixed space for the copper wire, and a fixed fraction of that space occupied by copper (not including air and insulation), then changing the wire size and corresponding number of turns will not affect the power consumed by the electromagnet at a given field strength.  More turns of smaller wire will need a higher voltage at lower input current to achieve the same number of ampere-turns and require the same power.