Electromagnet help please?

NUMB_NUTS

HI EVEYONE,
NEED TO TAALK TO SOMEONE WHO IS UP ON CALCULATING THE VALUE OF (B), REQUIRED TO LIFT A PLATE OF XXNEWTONS. ALSO ESTIMATE THE M.M.F REQUIREDTO LIFT THE SAME PLATE.
ANY TAKERS PLEASE?
THANKS

berkeman

No need to yell. What are the equations that describe the force generated by current flowing in a coil?

NUMB_NUTS

I WILL TRY EXPLAIN MY QUESTION AND PRESENT YOU WITH ALL THE FACTS I HAVE AT MY DISPOSAL.
In the question it is first mentioned that the pull,P, exerted at each pole of the magnet is given by the equation:
P = Bsquared x A divided by 2 x permeability of free space.
A being CSA of the pole faces
free space being 4 x pie x 10 to power of -7.

OK.
next we have c.s.a of magnet: 22 x 22 cm.
R, radius: 0.5m.
angle in degree`s: 120.
relative permeability of magnet: 2000.
relative permeability of plate: 1000.
thickness of plate: 5cm
weight of plate: 10'000 Newtons.

I have drawn out a diagram to show you what the radius and angle are all about. Can i paste a paint document here? It would help a lot.
Many thanks .

LM741

just save the the jpeg file on your computer and then attach it to the post.

NUMB_NUTS

electromagnet question.doc

Q1, I need to calculate the value of B required to lift a plate.
Q2, Estimate the mmf F required to lift the same plate.

I understand P = B squared x A. divided by 2 x permeability of free space.

This is what I have to work with:

The plate to be lifted weighs, 10`000 Newtons
Relative permeability of plate, 1000
Thickness of plate, 5 cm.

c.s.a. of magnet, 22 x 22 cm.
radius (mean) of magnet, 0.5m ( shown as red circle)
angle in degrees, 120.

I am assuming you have to first calculate the distance between the 2 poles. Using the cosine rule I make it: 0.75metres.

Now I need help with the rest please.
I don’t just want the answer I want to understand the formula properly.

Many thanks.

Ouabache

Can you define more clearly, the units for each of the variables in your expression
[tex]P = \frac{B^2 A}{2 \mu_o}[/tex]

by the way, your expression looks similar to one I note on this page. Are you using the same units?

From your given information, I don't see a value for "magnetic flux density" B. Perhaps you have some given information from which you can derive B.

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NUMB_NUTS	Electromagnet help please? Tweet HI EVEYONE, NEED TO TAALK TO SOMEONE WHO IS UP ON CALCULATING THE VALUE OF (B), REQUIRED TO LIFT A PLATE OF XXNEWTONS. ALSO ESTIMATE THE M.M.F REQUIREDTO LIFT THE SAME PLATE. ANY TAKERS PLEASE? THANKS

berkeman Mentor	No need to yell. What are the equations that describe the force generated by current flowing in a coil?

LM741	Electromagnet help please? just save the the jpeg file on your computer and then attach it to the post.

Ouabache Blog Entries: 2 Recognitions: Homework Help Science Advisor	Can you define more clearly, the units for each of the variables in your expression [tex]P = \frac{B^2 A}{2 \mu_o}[/tex] by the way, your expression looks similar to one I note on this page. Are you using the same units? From your given information, I don't see a value for "magnetic flux density" B. Perhaps you have some given information from which you can derive B.