What is Electromagnetism: Definition and 842 Discussions
Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, and it is responsible for electromagnetic radiation such as light. It is one of the four fundamental interactions (commonly called forces) in nature, together with the strong interaction, the weak interaction, and gravitation. At high energy, the weak force and electromagnetic force are unified as a single electroweak force.
Electromagnetic phenomena are defined in terms of the electromagnetic force, sometimes called the Lorentz force, which includes both electricity and magnetism as different manifestations of the same phenomenon. The electromagnetic force plays a major role in determining the internal properties of most objects encountered in daily life. The electromagnetic attraction between atomic nuclei and their orbital electrons holds atoms together. Electromagnetic forces are responsible for the chemical bonds between atoms which create molecules, and intermolecular forces. The electromagnetic force governs all chemical processes, which arise from interactions between the electrons of neighboring atoms. Electromagnetism is very widely used in modern technology, and electromagnetic theory is the basis of electric power engineering and electronics including digital technology.
There are numerous mathematical descriptions of the electromagnetic field. Most prominently, Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
The theoretical implications of electromagnetism, particularly the establishment of the speed of light based on properties of the "medium" of propagation (permeability and permittivity), led to the development of special relativity by Albert Einstein in 1905.
Homework Statement
What is the orientation of the loop relative to the magnetic field when the current has its maximum, and its minimum magnitude.
Homework Equations
Ohm's law & Faraday's lawThe Attempt at a Solution
The loop of wire is perpendicular to the magnetic field which gives it it's...
hey guys,
I know this might not be good for this part of the site, but I really am stuck.
I have this arabian prof for my electromag course, and his accent is so aweful that I get almost nothing from the class. at first I thought I might try to read it by my self, our textbook is milford's...
Homework Statement
One possible concern with MRI (magnetic resonance imaging) is turning the magnetic field on or off too quickly. Bodily fluids are conductors, and a changing magnetic field could cause electric currents to flow through the patient. Suppose a typical patient has a maximum...
In one of my old physics textbooks, there was a story about a scientist who was demonstrating electricity when it was a pretty new discovery. He had some sort of electrical device that he was showing and at one point he had it near a magnet. It didn't work as expected because of the magnet. The...
Can anyone please explain the concepts of scalar and vector potential and how they can be used to derive the wave equation for light?
References are welcome.
Thanks in advance for any help!
I am struggling to understand the relationship between electromagnetism, electromagnetic fields and electromagnetic radiation. I understand that a moving electric charge creates a magnetic field and a moving magnetic field creates an electric charge and that this is the foundation of...
Hi everyone,
I have been given an assignment with my physics subject and describe in 400 words how electromagnetism can be used to determine the composition of different chemical mixtures
I was hoping someone could lead me to a couple of websites to do my research. I have entered about...
Hey I am studying electromagnetism at the moment and one problem I'm having is the energy density.
Instead of typing everything out, this pdf has everything. http://www.physics.sfsu.edu/~lea/courses/ugrad/360notes11.pdf There are some things I don't understand. Why is the surface integral 0...
Hi.
Sorry my spelling, because I am not English.
Homework Statement
In a sphere truncated sector with an angle of 60 degrees, there is a uniform charge distribution, \rho. Calculate the electric field in (0,0,0). The sector starts in z=a and ends in z = b. The sphere center is in (0,0,0)...
Homework Statement
A sample of two different irons, Fe2+ and Fe3+, are accelerated by the same potential and then sent through the uniform magnetic field of a mass spectrometer.
a) Which ion moves faster after being accelerated? Justify your answer by referring to equations used in this lesson...
Homework Statement
Calculate the length l of an an iron-free cylindrical coil if it has 9400 turns (N), a thickness of 0.6cm and an inductance L = 68 mH. Take magnetic field constant \muo = 4\pi x 10-7 Wb/Am
(a) l = 63mm
(b) l = 54mm
(c) l = 46mm
(d) l = 36mmHomework Equations
L = N2 \muo...
Homework Statement
A hoop of radius R and total charge -q is oriented with its normal vector along the z-axis.
A positive charge +q is placed at the centre of the hoop. The potential at a distance r along the z-axis is:
V(r) = (\frac{q}{4\pi\epsilon_0}(\frac{1}{r} - \frac{1}{\sqrt{r^2 +...
Hello,
I want to know the right answers to these questions.
I will try to state my answers but I want to know if they are right or wrong.
Thanks.
Homework Statement
1.Does the Sun's mass decrease due to its radiating electromagnetic waves?
2.Does the speed of a light beam change as it...
Hello, I'm currently taking an upper level undergraduate Electromagnetism class and having some difficulty learning the concepts. We are using Griffith's edition and I must say I'm not a fan of the book, so I was wondering if anyone has any other books they could recommend, or even videos...
Given a propagating field expressed as E = Em Sin (wt - bz)j in free space, find the displacement (D) and the magnetic field (B) created by this electric field using a relevant maxwell's equation.
note : w is in fact omega
and b is beta.
j is a unit vector.
I don't know how I'm meant...
i am looking for an interesting book that explains electromagnetism and the actual science behind it and how it works. i do not know much about this subject so the book can't be to complicated.
A magnetic monopole, if it existed, would produce a magnetic field B = gr/r^3, where g is the magnetic charge, and r is the distance from the monopole. Calculate the angular momentum of a system consisting of a monopole g and a charge e, both at rest.
The attempt at a solution
I know...
Homework Statement
If the charge density increases linearly with distance from origin such that pv=0 at the origin and pv=10 C/m^3 at R=2, find the corresponding variation of D.
So we know that for R=0, pv = 0 and for R=2, pv=10 C/m^3.
We know that the charge density increases linearly from...
Here are two hypothetical experiments to illustrate my confusion...
#1
Two wires are positioned parallel to each other. A current is applied to both wires in the same direction. I would expect the 2 currents to each generate a magnetic field and that the 2 fields would interact to produce a...
Homework Statement
Two rods, of lengths l1 and l2, have charges q1 and q2
a)Find the charges per unit length for each rod individually.
b)Find the charge per unit length, averaged over both rods.
c)Check your result for l1 approaching 0
d)Check your result for l1=l2
Homework...
If observer A was at rest with respect to a charge that was moving with a constant velocity |v| > 0 in observer B's reference frame, would observer A detect a magnetic field?
Hi everyone, I'm trying to solve this prac design, but still don't know what to do, can anyone please give me some suggestions?
You are given an old cardboard box from Faraday’s, the bargain supermarket for electrical enthusiasts (“Everyday Low Charges”). The box contains
a battery,
...
Homework Statement
We are given surface current density, K which is constant (K is negative) along the z-axis which is placed in x=a plane (the board which contains this density is neutral), in x=0 plane there's an infinite plane which is charged by a surface density \sigma which is constant...
May a magnetic field exist w/o electricity? Yes, as lodestone shows us but where is the electricity? Electricity generates magnetism with it. So where is the electricity with lodestone?
n.b: The following is all math problems, dealing with vectors, I just need someone to check I'm doing the cross products and dot products properly< thank you! :)
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The electric field exerts a force per unit charge:
\bf{E} = (\hat{x} - 2\hat{y} + 4\hat{z}).
i) What is the magnitude of E...
Hi, I'm looking for the best book in which I can learn very well electromagnetism. I have good notions of all mathematics till differential equations. Furthermore I basically know analytical mechanics (I have studied on the Landau's Mechanics) and special theory of relativity.
Thanks in...
A stone is moving constantly in a horizontal motion in a uniform magnetic field in the direction pointing into the page. The field's strength is 1.7T. How fast does the stone have to move in order for it to remain moving horizontally without any vertical deviation?
For this quesion, using...
Homework Statement
A 20 turn wire that has a surface of 400cm^2 is rotating around an axe and is at a right angle to a uniform magnetic field of 0.3T. Find the average magnetic field induced if the speed of the rotation is 10 rotations/second.
Homework Equations
Faraday's Law...
In a particle physics formalism, electromagnetism can be described in terms of interchange of virtual photons.
The range is then c.t = hbar / E
with t the lifetime, and E the energy of the virtual particle.
What is the argument then, for long range EM interactions, in terms of E?
Is it...
1. A particle of charge q=6E-6C and mass m=1E-10kg is fired out of a charge gun towards the uniform magnetic field pointing into the page, B=0.50T. The particle moves vertically up originally and then accelerated through potential difference of 200V. There is a diagram of the B field going...
We know that a lot of electrical components associations are calculated using the harmonic average.
If we have parallel resistors we use the harmonic average. If we have serial capacitors we use the harmonic average too and so on...
But my question is: why the harmonic average? what does...
Ouch, had just written a big post when my university internet connection timed out on posting, so I'll keep this one short but powerful:
I came to the understanding E and B fields are modified when changing reference frames. But what about the following situation:
Charge q (named 1) is...
Homework Statement
Assume that Earth’s magnetic field is everywhere perpendicular to the path of a proton
and that Earth’s magnetic field has an intensity of 4.07 × 10−8 T.
What speed would a proton need to achieve
in order to circle Earth 1660.0 km above the
magnetic equator?
Answer...
Homework Statement
These are some general questions I have, related to an old assignment I am looking at.
1) Discuss the applications of polarisation in:
a. radio transmission across water
b. broadcast TV transmission
c. satellite communication
2) Explain why a plane electromagnetic...
Quick Question(s):
Who was it that tried to account for the EM force in terms of spatial curvature; i.e., who tried to expand GR in order to explain EM attraction and repulsion?
Also, on what grounds was his account refuted?
What's the difference between "repulsion force carrier and
attraction force Carrier" in electromagnetism interactions?
We know that these two messenger photons should be
distinguished. But in what features and details?
Q1) The amplitude of an electromagnetic wave is E0 = 471.0 V/m. Find the following values.
(a) Erms
333.047 V/m
(b) Brms
__ nT
(c) the intensity I
__W/m2
(d) the radiation pressure Pr
__nPa
Q2)(a) For a given distance from a radiating electric dipole, at what angle (expressed...
Homework Statement
The magnitude of the magnetic field in teslas at a distance d from a long straight wire carrying a current I is given by the relation B = 2 X 10 7 I/d. The two long straight wires shown above are perpendicular, insulated from each other, and small enough so that they...
Hey there!
I was just listening to Richard Feynman on the way home and hit yet another issue I have with relativity... I'd be most thankful for any input! :)
So, suppose we got two charged particles moving parallel to each other. A charged particle has an electrical field - if it's moving...
Hey everyone,
I just wanted to double check some solutions and inquire about a problem.
Homework Statement
A toroid is a coil of wire wrapped around a doughnut-shaped ring (a torus). For a tightly wrapped toroid with N turns, the magnetic field lines of \vec{B} form concentric circles...
Homework Statement
You are informed that the charge density is:
$\rho \left( r \right)=k{{r}^{-n}},r<a$,
where k is a constant and n is a whole number.
Determine n.
Homework Equations
Besides that, I know that:
\[E=\frac{Q}{4\pi {{\varepsilon }_{0}}}\frac{1}{{{r}^{2}}},r<a\]
(E is...
Programmer-turned-amateur-physicist here.
I'm reading Feynman's lectures, but I'm urged to do some physical experiments. The thing is, I have no idea about the practical side of things. Could someone write me a detailed description of some experiment? Say, the one with the hanging wire and the...
Four resistors are connected to a battery as shown in the figure. The current in the battery is I, the battery emf is emf, and the resistor values are R1 = R, R2 = 2R, R3 = 4R, and R4 = 3R.
Picture:
http://www.webassign.net/serpop/p21-32.gif
(a) Rank the resistors according to the...
In studying the world, physicists found that, in order to completely understand what today we call "Electromagnetism", it was necessary to do three things: find an equation which describes the electric field under all circumstances, find an equation which describes the magnetic field under all...
I need help designing some build-from-scratch DC motors. I'm looking to build really robust motors that I can be be sure will demonstrate clearly the principles involved, but that can be modified by my boys and that they can really *play* with and use to run simple toys. I've already shown...
Hello to everyone. I'm quite new here and I just wish I have found this site sooner. I am currently enrolled in Physics 2 class (Introductory) and we have just started Electromagnetism. Quite frankly, I am here to ask for some guidance as I am very weak in Physics. The only reason I passed...
Have exam tomorrow. I know I should have studied before and more, but please help. If you know the answer, please take some time to reply. Thanks very much.
Homework Statement
There are two charges, q1 = +4.5nC, and q2, ?, which are at distances d1 = 2.5cm and d2 = 2.0cm, from a point...
Can anyone please answer, and if possible, explain, this question? Thanks
1. A battery is connected between A and B of a bar made of semi-conductor of type P. The positive electrode was connected in A and the negative in B. What's the current direction?
A. from A to B
B. in the semiconductor...