Question

Magnetic potential energy?
Can someone explain this formula for me?

Answer 1

\[U(\theta)= -\mu . B \]

What is a magnetic moment?

Answer 2

@electrokid @gleem @Jemurray3 @zaphodplaysitsafe

Answer 3

When a magnet has more "mass" does it have a higher magnetic moment?
What does the "magnetic momment" do exactly?

Answer 4

magnetic moment is an intrinsic property of a magnetic dipole.. from the expression you understand that if you keep a magnetic dipole in a uniform mangetic field B then there will be potential energy stored in it.. wht does the potential energy depend on?? i would like to parallel it with gravity!!

a) in gravity potential energy depends on g acceleration due to gravity, so thats the gravitational field

similary here it depends on the B magnetic field strength

b) it depends on the HEIGHT..(or position) similary here it depends on the ANGLE (if the dipole is ALIGNED along B potential energy is min.. (angle is zero).. just like if an object is on ground we would say its potential energy is min.
similarly bigger the angle you make more the potential energy stored it.. just like HIGHER you go.. more the potential energy..
but here the highest you can go is 180degrees, so thats the max

c) it depends on the mass of the object. which is an intrinsic property of that object.. bigger mass bigger potential energy

SIMILARLY.. here it depends on magnetic moment which is the INTRINSIC property of the magnetic dipole.. MORE the magnetic moment more is the potential energy


so for gravity

U = mgh
here U = -(mu)Bcos(theta)

hope that helps!

Answer 5

on point C) the larger the magnet is, the higher the moment the greater the potential energy?

Answer 6

If mass is increased what happens to the moment?

Answer 7

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magpot.html

Answer 8

Thanks @M_Vamshi_Kumar_Reddy
But still:

"If mass is increased what happens to the moment? "

Answer 9

The momentum stays the same. The mass increases and the velocity decreases but the momentum stays the same, momentum is conserved.

Answer 10

Momentum increases unless the object is at rest. If so, the momentum will equal zero because the mass of an object multiplied by its velocity gives you momentum.

Answer 11

The momentum of a body is defined as:

momentum= Mass * velocity

So for any body and a given velocity, the momentum is directly and linearly proportional to its mass, that is if you increase the mass of a body then its momentum will increase by an amount of:
(M2-M1)* velocity

Where:
M2: Mass after increase
M1: Initial Mass

Answer 12

lol.. he is talking about MAGNETIC MOMENT.. not momentum

and besides i think ... I THINK not sure.. that if mass of the magnet were to increase, its magnetic moment would increase because now it has more atoms thus more dipoles!

Answer 13

The magnetic moment has nothing to do with mass.

Answer 14

why wouldn't it?! why can't we think of it that way!?/ more atoms, more dipoles hence more moment?!

Answer 15

Because you're immediately thinking of a bar magnet. If I take a wire loop and run current through it, that's a magnetic dipole.

Answer 16

yea well he is talking about bar magnet!

Answer 17

An electromagnet can also produce a dipole field, and I didn't see "permanent magnet" anywhere in the above discussion.

Answer 18

The term "dipole" refers to the type of field that the object produces. A dipole field looks like this:


And the magnetic field produced depends on the distance from the dipole as well as its dipole moment, which is a measure of its strength.