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".
i have an intuition of electric field lines, and force. All quantities yielded from an operation between two quantities should hold meaning. what meaning does the value "q x d" hold? I'm looking for intuition/ an intuitive grasp of the dipole moment.
I think everybody here knows the equation that gives the potential of a point like dipole, but how does the field look like if you have e.g. a metal sphere with radius $R$ and a certain dipol moment, how does this potential look like?
I am calculating the dipole moment of a metal sphere in a uniform electric field E_0 in z-direction. From here I know that the charge density [look at page 15][1]
[URL="[PLAIN]http://www.phy.iitb.ac.in/~dkg/PH-102/conductors.pdf"]http://www.phy.iitb.ac.in/~dkg/PH-102/conductors.pdf[/PLAIN]...
How they know, how to see the spin of electron>??
Without external field applied, there is random dipole in the paramagnet.
for diamagnet, without external field , there will be no dipole exist.
Thanks.
Hi everyone,
we haven't discussed this topic in our lecture but this task could be in the final exam so I'd need some help with it.
Homework Statement
Two dipoles with the dipole moment p are given. The distance between these two is d.
Find the potential as well as the electric field from...
Homework Statement
An electric dipole is located along the y-axis as shown in (picture attached). The magnitude of its electric dipole moment is defined as p=2aq.
(a) At a point P, which is far from the dipole (r>>a), show that the electric potential is
V=\frac{k_{e}pcosθ}{r^{2}}
(b)...
I have read about Biot-Savarts law but I have no idea how to solve it when the curve is dependent of some variable. My books in mathematics don't help, nor my books in physics. You are welcome to give me a link where I can read about this, but first let me know if I have got it right this far...
Homework Statement
There are three charged line segments, each with linear charge density λ, extending from the origin to (a,0,0), from the origin to (0,b,0), and from the origin to (0,0,c).
a) Find the dipole moment of this charge distribution.
b) Find the first two terms in the...
How to calculate the magnetic dipole moment??
Does anyone out there know how I can calculate the magnetic dipole moment of a simple bar magnet?
Or any kind of magnet?
Without using this formula: \tau = μ x B
Homework Statement
Calculate the force acting on a dipole of dipole moment P due to a line charge of density λ
at a distance r from it??
Homework Equations
field due to a line charge= λ/2εr
The Attempt at a Solution
tried caculating force on each individual charge but i don't see...
Hello.
I am currently studying scattering theory in detail for my BSc thesis, and I'm starting with Rayleigh scattering. I'm following Scattering of electromagnetic waves: theories and applications by L Tsang, J A Kong and K-H Ding, which is pretty much what I like in a science textbook...
How does the dipole moment effect the 'badness' of a greenhouse gas molecule?
The following link describes what a dipole moment is and how is sums up the bond polarity of a molecule...
An electron as shown by the Stern Gerlach experiment behaves like a dipole (albeit only in one of two states). I have been trying to figure out how this is so and drew up the following sketches. A few assumptions were made about electrons such as 'distribution' of charge assuming static...
Hi.
I'm having some difficult in understanding something about the dipole term in a multipole expansion. Griffiths writes the expansion as a sum of terms in Legendre polynomials, so the dipole term in the potential is writen
\frac{1}{4 \pi \epsilon r^{2}}\int r^{'}cos\theta^{'}\rho dv^{'}...
Homework Statement
Homework Equations
The Attempt at a Solution
I found dB/dr to be constant near r = 0, so it's a straight line, implying B increases linearly with r near r = 0.
For the second part, I assume the setup is as such, if not placing the dipole with its axis parallel to the coil...
Hi everyone, I'm a new member but it's not the first time I look at the forum.
Well, I don't know if this is the right section to post my question. I think it is related to quantum mechanics interpretation too. Anyway, let's have a look at my problem.
I've computed cross section for photon...
I can do this derivation the old fashioned way, but am having trouble doing it with einstein summation notation.
Since \vec{B}=\nabla \times \vec{a}
\vec{B}=\mu_{0}/4\pi (\nabla \times (m \times r)r^{-3}))
4\pi \vec{B}/\mu_{0}=\epsilon_{ijk} \nabla_{j}(\epsilon_{klm} m_{l} r_{m} r^{-3})...
Homework Statement
It's me again..
I solved this question but i want to be sure about it,so what do you think about my solution bellow?
a dipole consists of a positive charge q at x=d/2 and a negative charge -q at x=-d/2 (d is the distance between the charges). What is the potential produced...
The problem:
You and your engineering crew are in charge of setting up a wireless telephone network for a village in a mountainous region. The transmitting antenna of one station is an electric dipole antenna located atop a mountain 2.00 km above sea level. There is a nearby mountain that is...
I was reading the calculation for calculating the electric field due to a dipole at any point P at a distance x from the center of the dipole.
the way they have written the calc. seems a bit illogical
they have broken p into two components pcosθ and psinθ and applied E = kp/r3
Now...
Greeting PF!
http://chemwiki.ucdavis.edu/Physical_Chemistry/Atomic_Theory/Dipole_Moments
On the website above, I found an equation for the dipole moment of water:
"...the net dipole moment =2(1.5)xcos(104.5/2)=1.84 D."
I understand how to calculate the bond dipole. But after...
Hello all,
I am so confused on why a net torque on a dipole in a uniform electric field would not be equal to zero. Wouldn't one end rotate clockwise, the other counterclockwise and cancel out to zero?
Thanks.
Generally the concept of dipole moment is used in neutral system, ie the total positive charge equals to the total negtive charge.
Could the concept and also the calculation be used in charged system?
For example, NaOH, (Na+)(O-2)(H+), we can calculate its dipole moment.
Could I calculate...
Homework Statement
Water relative permitivity is about 81. If the electric field E=x[V/m] (x unit vector) is inside the water, what is the vector P(dipole polarization per unit volume)?
Then
Assume that the density of water is 1000 [kg/m3]
and that there are 3.34 × 1025 molecules per...
I'm currently writing a report on antennas and I am really struggling to understand the theory.
Here's what I've got so far;
Basics:
.A moving charge causes a magnetic field
.If the direction of movement is reversed, so is the direction of the magnetic field
.A non moving charge has...
Homework Statement
a hertzian dipole antenna has a length of 5 mm and carries a 50 MHz current of 2 A. Find the magnitude of the electric and magnetic fields at a distance 15 cm away from the antenna and theta=30 degree.
Homework Equations
Attached the equations
The Attempt at a...
Homework Statement
I'm not sure how they got the components of the B-field in the r and θ direction. I know the B-field along the ∅ direction is zero though.
The Attempt at a Solution
Here I have found the B-field at points P, Q and S that are very far along the z, x and y axis...
Homework Statement
The dipole moment of a water molecule is 6.29E-30Cm. What is the electric potential's magnitude 1.43nm from a water molecule along the axis of the dipole?
Homework Equations
p = qr
The Attempt at a Solution
I don't have values for q or r. I just know the...
Electric Dipole as x >> l, how do I simplify this correctly?
Homework Statement
ELECTRIC DIPOLE : 15.0 POINTS
A charge −Q is located at x=−l/2 and a charge +Q is located at x=l/2. Thus the separation between the two charges is l.
The total electric field on the x-axis can be written...
Homework Statement
See attachment
Homework Equations
The Attempt at a Solution
Thus far I believe I am supposed to use calculate the interaction with kQq/Δr? I have tried summing over interactions so that 1/4∏ε*[(-Q)(-q)/(r-d/2+D/2) + (-Q)(q)/(r+d/2+D/2) + (Q)(-q)/(r-d/2-D/2) +...
Homework Statement
Calculate the Electric field of a Dipole from its Potential.
\vec E=-\operatorname{grad}(\Phi_D)
Homework Equations
\Phi_D(\vec R)=\frac{Q}{4\pi\epsilon_0} \cdot \frac{\vec d \vec R}{R^3}
The Attempt at a Solution
Hi all!
I am trying to calculate the electric Field of a...
Homework Statement
A molecule with electric dipole moment ##\underline{p}## is initially aligned in an electric field ##\underline{E}## . If this molecule is perturbated from its equilbrium position by a small angle, show that it will perform simple harmonic motion.
Calculate the frequency...
Homework Statement
Point charges +4.70 and -4.70 are separated by distance 3.90mm, forming an electric dipole.
The charges are in a uniform electric field whose direction makes an angle 37.0 degrees with the line connecting the charges. What is the magnitude of this field if the torque exerted...
Homework Statement
Consider the following figure.
For the electric dipole shown in the figure, express the magnitude of the resulting electric field as a function of the perpendicular distance x from the center of the dipole axis. (Use the following as necessary: k, q for the charges, x...
I am simulating protons and electrons in a simulator that runs 1 femto seconds per second up to 1 second per second. So it can accurately show the passage of charge particles through space with data being updated on their displacement, velocity and acceleration.
However I am now adding in...
Hello, I have this problem. I calculated the dipole energy of a dipole moment in an external field using the equation U_m=\frac{1}{2}\int\vec{A}\vec{J}dr^3=\frac{1}{2} \vec{\mu}.\vec{B} however when the force on a dipole is calculated using \int\vec{J}\times\vec{B}dr^3 the formula...
I learn about Lamb-Chaplygin dipole and try to find the proof of this topic.
so I found the next link (is named: link1): https://docs.google.com/file/d/0B3-t1lLIJWOLc2NmT1RIWV9HOWs/edit?usp=sharing&pli=1
In addition, I found another link (is named: link2): http://ics.org.ru/doc?pdf=875&dir=e...
Hello everybody!
I am writing this topi because i got stuck in this!I have a cylindrical magnet with 1,5mm Radius,2mm thickness and Br 1,38 Tesla! I want to calculate the magnetic field in a distance s = [0 0 0.01](in meters) ,that means in 1cm distance while my magnet's position is α = [0 0...
Hi,
I don't understand this:
You got a dipole, and a resulting electric field from it like this(hyperphysics):
As z approaches infinity, the field becomes zero.
But if you draw a gaussian surface round the charges, then the net enclosed charge is zero.So the electric field must be zero, no...
With a 5W FM transmitter and a normal dipole antenna , to what range can I transmit. To be more specific, what will be the radiation pattern like (Can I get signal uniformly as in a circle where the center is antenna). Using which antenna, can I achieve maximum range omnidirectionally...
Homework Statement
For the dipole shown, the charges are ± 3.0 micro coulombs separated by a distance of 3.20 nm and oriented so that the theta is 35.0 degrees. If the electric field has a magnitude of 8000 N/C, find the magnitude and direction (clockwise/counterclockwise) of the net torque...
Homework Statement
I have attached the question as jpg to this post. Typing these were too time consuming and I uploaded the relevant sections as image files, thanks for your understanding.
Homework Equations
mu_0*epsilon_0*Poynting Vector = Momentum density
Position vector X...
I have some conceptual questions regarding capacitors and dipole antennas.
Consider a parallel plate capacitor made with two conducting plates, initially uncharged. If I connect each plate to a different terminal of the battery, charge will start to flow from one plate to another.
Consider...
I'm learning about an antenna theory and have a few question.
According to the attached image.
Can anybody explain what's going on in the image?
I've done lots of calculation, but still have no idea what's going on.
My question is
1. How dipole produce a loop of electric field...
Hi
I am reading a paper (http://arxiv.org/abs/0901.3105), where they after eq. (3) mention something I can't understand. First of all, (3) comes from the master equation of a collection of N atoms in a cavity. They say that (page 2, right after (3)):
The last term describes the coupling of...
Homework Statement
Two electric dipoles, oriented as shown in the figure, are separated by a distance r.
What is the force on p1 due to p2
Homework Equations
F = (p dot ∇)E
The Attempt at a Solution
I'm confused on the p dot ∇ part.
How is the divergence of p not just...