In electromagnetism, there are two kinds of dipoles:
An electric dipole deals with the separation of the positive and negative charges found in any electromagnetic system. A simple example of this system is a pair of electric charges of equal magnitude but opposite sign separated by some typically small distance. (A permanent electric dipole is called an electret.)
A magnetic dipole is the closed circulation of an electric current system. A simple example is a single loop of wire with constant current through it. A bar magnet is an example of a magnet with a permanent magnetic dipole moment.Dipoles, whether electric or magnetic, can be characterized by their dipole moment, a vector quantity. For the simple electric dipole, the electric dipole moment points from the negative charge towards the positive charge, and has a magnitude equal to the strength of each charge times the separation between the charges. (To be precise: for the definition of the dipole moment, one should always consider the "dipole limit", where, for example, the distance of the generating charges should converge to 0 while simultaneously, the charge strength should diverge to infinity in such a way that the product remains a positive constant.)
For the magnetic (dipole) current loop, the magnetic dipole moment points through the loop (according to the right hand grip rule), with a magnitude equal to the current in the loop times the area of the loop.
Similar to magnetic current loops, the electron particle and some other fundamental particles have magnetic dipole moments, as an electron generates a magnetic field identical to that generated by a very small current loop. However, an electron's magnetic dipole moment is not due to a current loop, but to an intrinsic property of the electron. The electron may also have an electric dipole moment though such has yet to be observed (see electron electric dipole moment).
A permanent magnet, such as a bar magnet, owes its magnetism to the intrinsic magnetic dipole moment of the electron. The two ends of a bar magnet are referred to as poles—not to be confused with monopoles, see Classification below)—and may be labeled "north" and "south". In terms of the Earth's magnetic field, they are respectively "north-seeking" and "south-seeking" poles: if the magnet were freely suspended in the Earth's magnetic field, the north-seeking pole would point towards the north and the south-seeking pole would point towards the south. The dipole moment of the bar magnet points from its magnetic south to its magnetic north pole. In a magnetic compass, the north pole of a bar magnet points north. However, that means that Earth's geomagnetic north pole is the south pole (south-seeking pole) of its dipole moment and vice versa.
The only known mechanisms for the creation of magnetic dipoles are by current loops or quantum-mechanical spin since the existence of magnetic monopoles has never been experimentally demonstrated.
The term comes from the Greek δίς (dis), "twice" and πόλος (polos), "axis".
The Great Attractor has been a source of controversy since its discovery. Some think it is just a fluke, others feel it to be a clue to a greater mystery. This paper; https://arxiv.org/abs/1702.02483, The Dipole Repeller, offers a deeper look without necessarily resolving the enigma.
Recently, I read a few popularized articles portraying a study and associated calculations using astronomical measurements that posits a characterization of the direction and acceleration (or velocity) of our galaxy. The researchers assert not only is our galaxy being attracted by massive...
Homework Statement
A dipole with charges ±q and separation 2a is located a distance x from a point charge +Q, oriented as shown in the figure.
Part A:
Find an expression for the magnitude of the net force on the dipole in the limit x≫a.
Part B:
What is the direction of the net force...
Homework Statement
I am given this picture
and I know that |q1|=2nC, |q2|=5nC, d=1mm
I need to first find the total dipole moment of the system. Then I need to find an equation that represents the electric potential due to this net dipole moment for all (everywhere)
Homework Equations
p=qd...
I am a little confused as to why my book is saying that the potential energy of a dipole is 0 at 90 degrees relative to the electric field lines. When it has the stored energy to turn from 90deg to 0deg if no force is acting on it. Wouldn't it make sense to use 0deg as a reference point then?
An electric dipole p with arbitrary direction and is at distance a from plane infinite conductor at z=0.
Using the image of the dipole
##p=(2pcos\theta \hat{z}+psin\theta \hat{x}##
##p'=(2p'cos\theta \hat{z}-p'sin\theta \hat{x}##
Using the...
Homework Statement
We're given a situation where the circuit can move under the influence of a magnetic force. Now I need to show that the force on the magnetic dipole is
Homework Equations
$$\vec{F} = (\vec{m} \nabla) \vec{B} $$
The Attempt at a Solution
Could I start from a given Force for...
I came across these videos that show how electric field looks around the dipole antenna at three different distances
Far field
Near field
Something between far and near field
That got me thinking - there is a point when the field is reversing and the electric field closes into a loop and...
Homework Statement
Find the force of attraction between 2 magnetic dipoles a distance r apart. Both dipoles point to the right.
Homework EquationsThe Attempt at a Solution
All I need help with is figuring out how to determine if the force is attractive or repulsive between the 2 dipole...
hi,
my question is in regard of a printed (microstrip) dipole antenna.
I know that a balun acts as an unbalanced to balanced line transformer.
(in my case of the dipole antenna: the coaxial feed is unbalanced and the half-wave diple antenna is balanced, so i need a balun.)
But what exactly does...
The following mechanism leads me to wander that a moving neutral object (compose from atoms) in vacuum may generates electric filed due to very small dipole moment.
I propose that when atoms force to move in a certain direction the force propagates within the atom. A retardation in movements...
It isn't difficult to find the electric field of a dipole.
However, it is tricky to find the field lines. All points of a field line have to be parallel to the electric field at those points. A tangent, which is the derivative, is parallel.
We can hence formulate the equation for a field line...
Homework Statement
Compute the force between two identical dipoles. See Problem P63 on page 544 to set up the problem. Explain why this result makes sense by comparing it to the force between two point charges and the force between a point charge and a dipole, in terms of the relationship to...
When solving the differential equations for an electromagnetic wave you get out that the electric and magnetic field oscillate in phase.
But when considering a oscillating dipole, the electric and magnetic field at a point close to the dipole are a quater period out of phase.
Can someone please...
Hi.
An electric dipole field (two opposite point charges separated by some distance) has fields lines from the positive to the negative charge, but also field lines reaching to and coming from infinity. Starting from the positive charge, is there a way to compute the opening angle of the cone...
Homework Statement
An electric dipole consists of +/- Q = 330nC separated by a distance of 1200nm. The dipole is initially oriented in the -i direction (along the negative x axis). The dipole is in a uniform external electric field of E=2500j N/C Determine the following:
a) The magnitude of...
Homework Statement
Consider the charge distribution of a uniformly charged ring of radius ##R## and charge ##Q## at a distance ##d## above the origin and a uniformly charged ring of radius ##R## and charge ##-Q## at a distance ##d## below the origin.
(a) Calculate the dipole moment of this...
Homework Statement
I want to determine the net force and torqe on a moving electric dipole in non-uniform magnetic field.
I suspect I should take some kind of a limit, but I'm not sure how to do so.
Please help, I'd really like to understand this.
Homework Equations
##\mathbf{F} = q \mathbf{v}...
Homework Statement
Hi everybody! I'm trying to solve a problem about dipoles, but there is something I don't quite get about it. Well, first here is the problem:
An electric dipole ##\vec{p}_1## is placed at the zero-point and shows in the z-direction. A second electric dipole ##\vec{p}_2##...
I was going through the chapter Chemical Bonding in one of the books and found something about orbital dipole due to lone pairs.
In each diagram the orbital dipole due to lone pair was directed from the central atom to the end of the hybridized orbital (lone pair).
Why is that so?
Say I place a magnet on a table, and I have a metal in close proximity. Will its magnetic field change due to the presence of this metal, however minute?
What if I had another magnet or the table itself is made of materials the magnet is slightly attracted to? Does this phenomenon even exist?
Hello PF!
I am trying to find out how the formula for the magnetic field of a dipole magnet is derived, so far I've delved into maxwell equations, but I am finding the math too complicated to read. My state's education system is very far behind, and I am not accustomed to characters and symbols...
Im looking to find the resultant magnetic moment of a permanent magnet inside of a steel housing. Some of the remnant flux density is absorbed by the magnet and the field is altered. I want to figure out the total magnetic dipole including the presence of the steel housing. I've been using...
Homework Statement
Consider the electric dipole seen in the notes. (a) Using integration, derive an expression for the magnitude of the electric field produced by the dipole at any point along the x-axis.
Electric Dipole: http://labman.phys.utk.edu/phys136/modules/m5/images/electr5.gif...
I've been recently trying to understand the concept of paramagnetism, but I feel like I'm running into 2 conflicting models.
Stern–Gerlach seems to suggest that electron spins always point up or down to an incident magnetic field, regardless of their spatial orientation. Similarly, when...
Hello,
Is it possible to derive the electric field of a dipole antenna mathematically?
Does it look like a pure dipole far away?
I am experimenting with these things and they are a bit mysterious to me.
Thanks for your answers!
Homework Statement
To derive Potential Energy for dipole p in Electric Field E.
2. Homework Equations
Potential Energy is the work done by the external agent in turning the angle of the dipole from the U=0 position to another position against the influence of the electric field applied...
Homework Statement
Given a sphere with radius R, centered at (0,0,0), it's dipole density given as ##P\left(\vec{r}\right)=\alpha\left(R-r\right)\hat{z}## where r is the distance from the center of the ball.
I'm required to find:
Bound charge density inside the sphere, bound charge density on...
My teacher posted on his website, Lewis structures of different compounds. One of them were N3-
Why isn't there a dipole moment arrow pointing from the central atom to the other Nitrogen? Does the arrow only point from neutral atom to negatively charged atom?
Can someone describe for me the dipole pattern that was detected related to the fine structure constant? This thread talks about that pattern some. What I am trying to understand is how that dipole is oriented relative to the observer on Earth? Are we talking about a toroidal shape with a...
Homework Statement
Hi everybody! I might have solved that homework but I struggle to properly understand some steps, especially concerning the gradient and partial differentiation:
The potential Φ(r) of an electric dipole located at the origin of a coordinate system is given by:
\phi...
The analysis of the distribution of spins for a paramagnetic solid in a B field shows that the probability of a dipole being aligned/anti-aligned with the B field ##\to 0.5## as ##T \to \infty##.
The intuitive justifications that I've read say that this is "expected" as thermal motion tends to...
Hello everyone! :)
I'm sorry that I'm posting something that might be obvious, but I'm still struggling to capture all the concepts behind the fundamental physics of this model.
Let's say, I have a 2D sheet of graphene, on which, there's a physisorbed layer of molecular dipoles (vdW bonding...
Is the magnetic dipole moment, the torque a material experiences when its placed in an external magnetic field?
I know that the magnetic dipole moment for a current carrying wire is U=IA.
The dipole moment is in the same direction of the Area, does this mean that the force it experiences will be...
Homework Statement
A thin rod of length 2L has a linear charge density that isλ0 at the left end but decreases linearly with distance going from left to right in such a way that the charge on the entire rod is zero.
Given
E = −kλ0/L(d/(L−d)−ln(d−L)+d/(L+d)+ln(L+d))
for a point P that is...
If you consider an electric dipole, why is it that there is any space between the two particles at all? If both particles of opposite sign attract to each other with equal magnitude, shouldn't they just stick together?
Hello!
I will be grateful for the explanation on why NCl3 has a dipole-dipole intermolecular force, if, based on electronegativity difference, or rather the absence of such, (both N and Cl have 3.0 electronegativity) this is a non-polar bond?
Thank you!
1- Potential energy stored in a dipole placed in an electric field E is maximum when
a- E is perpendicular to the dipole moment b- E is parallel to the dipole moment
c- E is anti-parallel to the dipole moment
Homework Statement
Greetings.
Can someone give me hint how to solve following problem:
Homework Equations
From my understanding, you need following formula to solve problem:
and then potential can be obtained by integrating over the current distribution.
But right now these foormuas really...
Let's say we have a north south bar magnet and we place it in a uniform magnetic field such that the magnetic moment is perpendicular to the magnetic field.
What happens to the orientation of the magnet?
In my view, the magnet receives a torque pointing out of/in to the page that causes the...
Hi everyone,
I am interested how is polarized light absorbed by a molecule or an atom. Unfortunately, I come to a problem in the derivation where a complex vector in a real space appears. This is something I never seen before and I do not know how to interpret it. Therefore I would like to ask...
I recently completed a lab over magnetism and I need some help on my results. We were asked to find the magnetic dipole moment of small neodymium magnets that were about the size of a dime and around 1/4 inch thick. I found the experimental value using my results. However, I have not been...
Homework Statement
Consider the following pair of dipoles in one dimension.
One of the dipoles: -ve dipole positioned at (-D/2, 0) and +ve (+D/2, 0), with the origin between them.
Other dipole: -ve dipole positioned at (r-d/2, 0) and +ve at (r+d/2, 0), with (r, 0) being the centre.
Show that...