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".
Homework Statement
Compare Dipole moment of CH3F and and CD3F where D is deuterium.
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Theory questions
The Attempt at a Solution
Our sir had explained that to do this question we muat take into account the vibration of the atom in the respective molecule.
That is that the...
Hello, I've been reading up on this topic and have a couple of questions. This videos shows what I am referring to:
1. What makes the electromagnetic waves from a dipol antenna spread out? There would have to be some type of force that pushed them outwards, right?
2. When the electromagnetic...
Homework Statement
ok this is not a homework but i am confused by the derivation of ## f = \nabla (m . B)##
both start out with ##\vec B(r) \approx \vec B_0 + (\vec r' . \nabla)\vec B|_0 ... \\
f = \iiint_{v'} \vec J( r') \times (\vec r' . \nabla)\vec B|_0
##
where prime is body coordinates and...
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Problem attached in Dipole.JpgHomework Equations
The Attempt at a Solution
I am fine with Part A of the problem. I am just trying to understand what part B is asking. Are they asking what is the magnitude and direction of the dipole vector associated with charges q1 and q1 at...
Ok so she says that electric dipoles are of opposite charge but equal magnitude at 3:40. But then at 5:33 she shows 2Q with -Q, at that point the magnitude of the 2Q particle wouldn't be equal to the -Q so they wouldn't be electrical dipoles right?
In this derivation:
https://cpb-us-e1.wpmucdn.com/sites.northwestern.edu/dist/8/1599/files/2017/06/taylor_series-14rhgdo.pdf
they assume in equation (8) that x >> a in order to use the Taylor Expansion because a/x has difficult behavior. Why does that assumption work? Meaning, why can we...
Consider the magnetic field B generated by a magnetic dipole. The intensity of B measured along the
axis of the dipole, at a distance of 10 cm from the dipole itself, is 1.0 10-5 T. What is the size of the
magnetic dipole moment? (μ0 =4π10-7 mkg/C2)
a) 0.050 Am2
b) 5 10 -4 Am2
c) 0,1 Am2
d) 1 10...
I'm trying to understand calculation made Robert Zubrin in his presentation on Dipole Drive
source:
In here he made the following statement
"A Coulomb of protons has a mass of 0.011 milligrams. If the jet power is 400 W, and the potential difference is 64 V, so the proton current will be...
Homework Statement
I'm given that there is a positive charge of 1 nC at x=0.25 m and a negative charge of -1 nC at x=-0.25 m. I've calculated the potential created at different points along the x-axis by the positive charge and the negative charge using the formula, $$V=\frac{kq}{|r|},$$ where...
Hello! I am reading Griffiths derivation for the electric dipole radiation (actually my question would fit for the magnetic dipole radiation too). He considers 2 charged balls connected by a wire with charge going back and forth between them. Now, when he calculates the vector potential he uses...
Homework Statement
A plane z=0 is charged with density, changing periodically according to the law:
σ = σ° sin(αx) sin (βy)
where, σ°, α and β are constants.
We have to find the potential of this system of charges. Homework EquationsThe Attempt at a Solution
[/B]
I...
Homework Statement
This is from Griffith's Introduction to Electrodynamics, where the book is deriving the magnetic dipole moment from multipole expansion of the vector potential
The vector potential of a current loop can be written as
$$\mathbf{A(r)}=\frac{\mu_0 I}{4\pi} \left[ \frac{1}{r}...
There is a big sphere with charges distributed on the surface. N charges are distributed on a patch of the sphere (all the information of the charges such as their locations are known). Suppose the rest of the sphere has similar charge distribution as the patch, how to approximately calculate...
When neutral atoms become polarized from ambient EM radiation, does this automatically imply that electrons have shifted orbitals,or do they remain in the same levels but become deformed? Thanks
I have been doing a study for a couple of years now on the off center fed dipole. I was very much in the dark on what to expect in the relationship between the off center fed (ocf) and a regular dipole. I asked many questions and most of the time I jumped to the wrong conclusions. I decided...
When the aminoacid environment were changed with adding OH or etc., Aminoacid N terminal were affected by H amount and in determined pKa, they loose hydrogen from N terminal. NH3 goes Nh2. My question is related to this. While this event occur, how change dipole moment of this terminal? Electron...
Homework Statement
A rotating magnetic dipole is built by two oscillating magnetic dipole moments, one along the y-axis and one along the x-axis. Find the vector potential at a point: (0, 0, ##z_0##) along the z-axis. Then find the magnetic field at ##z_0## . As the magnetic field is a function...
Homework Statement
An electric dipole instantaneously at rest at the origin in the frame K' has potentials \Phi'=\mathbf{p}\cdot\mathbf{r}'/r'^3 and \mathbf{A}'=0 (and thus only an electric field). The frame K' moves with uniform velocity \mathbf{v}=\vec{\beta }c in the frame K.
Show that in...
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:
2 Questions, sorry about this if It adds confusion.
1) How do I go about drawing Lewis Structure Diagrams? I've searched the web, but all I can find, even when they say it's a "Lewis structure" diagram is lewis dot diagrams. My teacher wants it in the specific form where...
Homework Statement
A spherical shell of radius R has a surface charge distribution σ = k sinφ.
Calculate the dipole moment of the spherical shell.
Homework Equations
P[/B]' = ∫r' σ(r') da'
The Attempt at a Solution
So I believe my dipole will be directed along the y axis, as the function...
The Magnetic Dipole Moment for a Magnetic Field for a dipole oriented on the x-y axis is:
##\bar m = |m| \hat z##
The Magnetic Field is:
##\bar B = \frac{\mhu_0}{4 * \pi * |\bar r|^5} * 3 * \bar r * (\bar m . \bar r) - \bar m * |\bar r|^2##
Vector Potential is:
##\bar A = \frac{\mhu_0}{4 * \pi...
This is from a lab where my team found the equipotential lines from the electric field of a dipole. The information I was given to calculate the magnitude of the electric field seems too simple, and for some reason I'm expecting this to be more complex. So, this is my attempt at double checking...
After solving a homework problem, I realized I don't know what to do when there's a dipole and a point charge but the distance from the charges in the dipole is greater than the distance from the center of the dipole to the charge. As my homework problem stated, with a little context added...
Hi all,
Consider one has a magnetic dipole, the field given by:
\begin{equation}
\vec{B} = \frac{\mu_0}{4\pi}\left(\frac{3(\vec{m}\cdot\vec{r})\vec{r}}{r^5}-\frac{\vec{m}}{r^3}\right)
\end{equation}
where we can take $$\vec{m} = m\hat{y}$$.
Let us say we have the a magnet vector which is...
Homework Statement
A charge Q is fixed at the centre of a train track, radius R. An electric dipole with charges Q, -Q, separated by distance d. Show that the net force on the dipole is given by F = Q2d/(4πε0R3)
b) What direction is this force?
c) What is the torque on the dipole?
Homework...
Hi all, this is my first time posting so I hope it's in the right place, if not I apologise. I'm trying to understand the angular dependence in NEXAFS spectroscopy for linearly polarised light.
So from what I understand, the quantum mechanical description of the excitation process for a single...
Homework Statement
Homework EquationsThe Attempt at a Solution
In case of uniform E, torque ##\vec N = \vec p \times \vec E
\\ U = \int_0 ^ \theta N d \theta = pE \int_0 ^ \theta \sin \theta d \theta = - pE \cos \theta
\text { Here, I assumed that the direction of } \vec N ~ and ~ \vec d...
Homework Statement
Homework Equations 3. The Attempt at a Solution [/B]
I have drawn this diagram using MS paint, could you please tell me some other software in which I can draw and insert greek symbols, too ?Let me take the origin at O.
## \hat r \left(\alpha\right) ≡ \hat r\text{ at...
Homework Statement
A very thin, finite, and uniformly charged line of length 10 m carries a charge of 10 µC/m. Calculate the electric field intensity in a plane bisecting the line at ρ = 5 m.
Homework EquationsThe Attempt at a Solution
Not sure why I'm not getiting this but I've been at this...
I have a question for the community. I am doing a further study and trying to locate any information regarding input impedance of an off center fed dipole at different heights above ground. A simple dipole targets 73.1 ohms for 1 wave length or higher above ground. I am not sure if the same...
Homework Statement
In an infinite flat layer of thickness 2d, volume charge density is given according to the law: ρ=(ρ°)(x)/d and (-d≤x≤d). Here, x is the axis perpendicular to the plane. In the layer, there is a thin channel in which a point dipole of mass m and dipole moment p is placed...
Homework Statement
I am trying to derive the dipole-dipole interaction derivation, which is:
U=(-p1p2/4πϵ_0) (1/z^3) ((2cosθ_1cosθ_2)− (sinθ_1sinθ_2cosζ))
Where p1 and p21 are the two dipole moments, r is the distance between two dipoles on the y axis, θ_1 and θ_2 are the angles between the...
I am trying to understand the magnetic dipole field via loop of wire.
The above pictures show how this problem is typically setup and how the field lines are typically shown.
The math is messy but every textbook yields the following:
β = ∇xA = (m / (4⋅π⋅R3)) ⋅ (2⋅cos(θ) r + sin(θ) θ)
The...
I am studying to about maxwell's equations on the electric and magnetic field.
First of all, just do the example and exercise: https://www.princeton.edu/ssp/josep...ide-to-maxwells-equations-D.-FleischLEISC.pdf
I have this dipole antenna...
I was watching a video explaining how microwave ovens work when I found that there is a difference between my physics textbook and online images of the electric dipole moment of the water molecule, as well as the one shown in the video.
Why do they differ?
Hello all, i am having a hard time with EM, specially with the most simple concepts that i don't seem to grasp at all and the simple exercises that should be quite simple to solve.
So the question is. ( i will omit the constant (1/4pieo) for practice sake
When i calculate the eletric field...
First time poster long time reader.
If i have a half wave dipole antenna with a certain length and I am using a VCO to drive that antenna at lower driving frequency do i get EM at the length of twice the length of the antenna but just at a slower emission rate?
example, if i have a half wave...
Hi everybody,
I want to ask a question about the dipole moment vector ##\vec{d}##, with components expressed in the molecule-fixed axis. By permuting identical nuclei that compose a rigid molecule, I know how ##d_x##, ##d_y##, ##d_z## change.
But when dealing with non-rigid molecule, I no...
Homework Statement
A cylindrical bar magnet whose mass is 0.08 kg, diameter is 1 cm, length is 3 cm, and whose magnetic dipole moment is <5, 0, 0> A · m2 is suspended on a low-friction pivot in a region where external coils apply a magnetic field of <1.4,0,0> T
You rotate the bar magnet...
Hi.
In this video around 6:45, this guy builds a simple dipole antenna with an LED and capacitor in parallel in the center. The LED flickers when close to a transmitting cellphone.
Since the LED only let's current pass in one direction, shouldn't this quickly lead to a charge imbalance between...
Homework Statement
Electric Dipole makes small oscillation is electric field find its ##ω##
Homework Equations
##τ=pEsinθ##
##τ=I∝##
The Attempt at a Solution
##τ=pEsinθ##
##τ=I∝##
so ##pEsinθ=I∝## which that's...
Hello Experts,
I have created this thread especially for clearing some of the important concepts of Antenna and Designing Issues.
I have a question for all of you, related to Dipole Antenna.
I have designed a Folded Dipole Antenna resonating at center Frequency of 145.800MHz.
This antenna is...
Homework Statement
An electric dipole with magnitude ##p = 0.2Cm## is placed inside a uniform electric field of ##\vec{E} = 100\vec{i} + 70\vec{j} + 40\vec{k} \frac {N} {C}##. The dipole was initially pointing along the +x direction. You then start to rotate it first on xz-plane towards...
Homework Statement
A point charge Q is held at a distance r from the center of a dipole that consists of two charges ±q separated by a distance s. The dipole is initially oriented so that Q is in the plane bisecting the dipole. Assume that r≫s.
A) Immediately after the dipole is released, what...
Homework Statement
The force exerted by a uniform electric field on a dipole is:
A) Parallel to the dipole moment.
B) Perpendicular to the dipole moment.
C) Parallel to the electric field.
D) Perpendicular to the electric field.
E) non of the above.
Homework Equations
Net force on dipole = 0 N...
Homework Statement
We have an electric dipole with moment P=2*[10][/-5] pointing in x direction. What is the force experieced by dipole at origin when a point charge Q=3*[10][/-4] is located at (0.014 m ,0,0)
Homework Equations
1. [E][/dipole]=(1/4π[ε][/0])(2p/r3)
2. p=qs
3. F=qE
4. τ=pEsinϑ...