Increase the IRON cores area?

[Vis99]

Is it possible to increase an electromagnet's size without changing its input to get the same magnetic field, force, as before?
Example:
Used 1W for an electromagnet with an area of 0.5"x0.5" can pull with 2N At 3V and 0.33amps,
Can I get another electromagnet the same in everything BUT THE SIZE, where in this case is larger. And limit the input power to get the same force as the smaller electromagnet?

The whole point is it increase the "area" to a larger one than before. Can that be done in all electromagnets?

 

[7anoter4]

You can increase the cross section of an electromagnet core but in order to maintain the lifting force you have to multiply w^2*I by sqrt(A1/A2) where:
w=number of coil turns; I the current flowing through the coil.
If you reduce the number of turns, the coil resistance and reactance will drop then
the current will grow up. By iteration you may find the point where w^2*I will be as required. See:

http://en.wikipedia.org/wiki/Electromagnet

F=B^2*A/2/miuo lifting force B-magnetic flow density A-iron core cross sectional area
In order to get the same F: B1^2*A1=B2^2*A2
B2=B1*sqrt(A1/A2)
B2=W2*I2*miuFe2/height w2=required no.of turns miuFe=iron permeability height=coil height
I=Volt/sqrt(R^2+X^2)
R2=ro/scu*w2*pi()*loop diameter
X2=2*pi()*frq*miuoFe*w2^2*A/height

 

[waross]

Remember; to change the strength of an electromagnet with the windings, you must either change the wire gauge or change the applied voltage.
With small changes in the number of turns consider a coil with 100 turns and 1 Amp flowing. 100 turns x 1 Amp = 100 Amp turns.
Now double the number of turns to 200 turns with the same gauge wire. The resistance will double so the current will be 1/2 Amp. 200 turns x 1/2 Amp = 100 Amp turns.
So more turns of the same gauge wire seems to have no effect on the magnetizing force. But wait, it gets worse.
More turns often means a greater average turn length with a proportionately greater resistance.
Two 100 turn coils in parallel will give almost twice the Amp turns and a stronger magnet.
Or
100 Turns of a wire with twice the cross sectional area as the wire used for two windings in parallel.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[electricpete]

Original question seems vague to me. First sentence talks about field and force constant... later you menation force again.

Which one do you want to keep constant.... force or flux density? You cannot keep them both constant.

As 7anoter4 said, the relationship betwen force and flux density for small gap between coil and an attracted iron piece:
F=B^2*A/(2*muo)

If you increase A, then the relationship between B and F changes.... so you can keep F constant or B constant but not both.

You talk about keeping "everything the same". What do you mean by everything? Your example focuses on input power - it depends on current and resistance. You can adjust resistance over quite a range by adjusting wire diameter.. is wire diameter part of "everything" that's not allowed to change? Is number of turns part of "everything" that's not allowed to change?





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(2B)+(2B)' ?

 

[waross]

There is a little more to the interaction of the properties of an electromagnet than can be explained by a few short tips. Your best course of action may be to spend some time with a basic text book on magnetism. It seems as if everything mentioned leads you further into unknown territory. It may be time for you to do some work on your own rather than looking for the "magic bullet" of instant understanding of a somewhat complex subject.

Bill
--------------------
"Why not the best?"
Jimmy Carter