In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electrical current) in one or more directions. Materials made of metal are common electrical conductors. Electrical current is generated by the flow of negatively charged electrons, positively charged holes, and positive or negative ions in some cases.
In order for current to flow within a closed electrical circuit, it is not necessary for one charged particle to travel from the component producing the current (the current source) to those consuming it (the loads). Instead, the charged particle simply needs to nudge its neighbor a finite amount, who will nudge its neighbor, and on and on until a particle is nudged into the consumer, thus powering it. Essentially what is occurring is a long chain of momentum transfer between mobile charge carriers; the Drude model of conduction describes this process more rigorously. This momentum transfer model makes metal an ideal choice for a conductor; metals, characteristically, possess a delocalized sea of electrons which gives the electrons enough mobility to collide and thus affect a momentum transfer.
As discussed above, electrons are the primary mover in metals; however, other devices such as the cationic electrolyte(s) of a battery, or the mobile protons of the proton conductor of a fuel cell rely on positive charge carriers. Insulators are non-conducting materials with few mobile charges that support only insignificant electric currents.
I need clarifications on the following points regarding a capacitor in general.
1.When you bring another conductor near a charged conductor, the capacitance of the latter is said to increase, because the presence of the second conductor near the first one lowers the potential of the former...
When we connect a battery across a loop of wire having some finite resistance there comes into picture an electric field E which is empirically given by J/sigma.(sigma==>conductivity).
but how can there exist an electric field inside a conductor??We had already learned that electric
conductor...
Homework Statement
A solid spherical conductor carries a charge Q. It is surrounded by a concentric uncharged spherical shell. The potential difference between the surface of solid sphere and the shell is V. If a charge of -3Q is given to the shell. Then the new potential difference between...
question
For a plane wave of the form E(z,t)=Ee^i(kz-wt) and B(z,t)=Ee^(-kz)*e^i(kz-wt) write down the time-averaged ohmic heating loss per unit volume for any z.
Homework Equations
J=\sigmaE
Maxwell's equations for linear media
The Attempt at a Solution
not sure where to start, i...
I'm curious why electrons will travel near the perimeter of a large wire as opposed to using the whole cross section. I understand that electrons flowing through the wire repel each other and thus want to be as far apart as possible. Yes, but from this electrons should not just occupy the...
Homework Statement
We are given that there is a hollow conducting sphere with a charge 1C (to simplify things) inside it and are asked to find the charge per unit area on the inner and outer surface of the sphere. Inner radius of the sphere is 1m and outer radius is 2m
Homework Equations...
The Hall voltage across a 0.800-mm-thick conductor in a 1.30 T magnetic field is 3.2 uV when the current is 12.0 A.
What is the charge carrier denisty in the conductor (in m-3).
I was using the equation Vh=IB/ned
where Vh is the Hall voltage
I is the current
B is the magnetic field...
Homework Statement
Show that there is a force of 0.1N on a conductor of length 100mm carrying a current of 10A at right angles to a flux density of 0.1T.
Show that 0.1J of work is done if the conductor is displaced by 100mm at right angles to its length.
Homework Equations
F=BIL...
In an infinitely long current carrying wire (assuming zero resistance) say there is a definite current.
"Having current in it" means there is a flow of charge in it, which means if positive charge moves in one direction then negative charge moves in opposite direction. As we know that a charge...
Homework Statement
v=qEt/m
t=time between each collision
q=charge on particle
m=mass of particle
E=electric field
Why is this the average velocity/drift speed in a conductor?
Homework Equations
The Attempt at a Solution
Doesn't qEt/m = the final velocity of the...
Homework Statement
A Spherical conductor has an Electric field near its surface of 180 volts per inch.
How much charge (in Coulombs) is on the sphere ?
How many excess electrons are on the sphere?
Will the air around the sphere break down and produce an arc ?
Homework Equations
Well, I...
Hi everybody...
I have a simple question for you..
Where can i found the expression of the magnetic field around at the conductor which it has finite lenght? because i always found the megnetic filed in a conductor infinite length ..
Sorry for the stupid question...
tanks and best regard
Homework Statement
The potential of a metal sphere of diameter 2 cm is 10^4 V relative to the ground.
a) What is the surface charge density?
b) How many electrons were removed from the sphere?
c) What is the electric field strength at the surface?
Homework Equations
The Attempt...
Homework Statement
a thin straight wire of length 0.4m is suspended from a spring balance. the scale reads 2g. the horizontal component of the Earth's magnetic field at that place is Bh=3*(10^-5)T. the wire is held horizontal and at right angles to Bh.if a current of 500A is passed through...
Homework Statement
The problem is simple: there is a coaxial cable where the current flows in one direction in the inside conductor and in the opposite direction in the outside conductor. I'm asked to find the magnetic field on a point situated in the space between the two (that space is...
Homework Statement
The figure shows a portion of an infinitely long, concentric cable in cross section. The inner conductor carries a charge of 5.1 nC/m and the outer conductor is uncharged.
What is the electric field 1.9 cm from the central axis? The permittivity of free space is 8.85419e-12...
Hi,
I am in Purcell's E&M book at the section explaining why the field is zero inside a hollow conductor of any shape. The proof given is that the potential function inside the conductor must obey Laplace's equation, and that the boundary of the region (in this case a rectangular metal box) is...
In a question there are two conducting shells of radii a and b (a<b),the outer shell is given a charge Q . And the inner shell is grounded then the potential of that shell was equated to zero and its charge was assumed q.
And it resulted in an equation
KQ/b + Kq/a = 0 this gave q = -(a/b)Q...
I beg you to understand my poor Eng..
If there is any poor grammar or spelling..please correct me..
While studying MHD with "An Introduction to Magnetohydrodynamics" written by Davidson,
I encountered the term 'current density'..
As you know well, empirically,
\mathbf{J} = \sigma...
Homework Statement
A conductor is aligned with Earth's magnetic lines of force. The compass set above the conductor points in a line parallel to the conductor. A DC power supply is connected to form a closed circuit with the conductor. Explain how this information could be used to identify the...
Homework Statement
Given an electrical dipole of electrical dipole momentum \vec P = p\hat k, centered in 0\hat i + 0\hat j + 0\hat k, find the potential in all the space, where V(\infty ) = 0. If the dipole is now surrounded by a hollow spherical conductor (initially discharged), find the...
The noise power in a conductor is given by
P = k.t.B
Does this mean the noise power is independant of the conductor length?
Also, does this only apply for a conductor with no resistance?
Thnks,
Rudi
In the case of a finite conductor rod moving at a constant velocity perpendicularly to a uniform magnetic field, E. Purcell says that the free charges in the rod suffer a force such that they move to an extremity of the rod. When in the final state, he says (at least this is what I understand)...
When finding the angles for the finite length Biot-Savart formula of a filamentary conductor H = I*(cos(α2) - cos(α1))aΦ/(4πρ), is α1 supposed to be calculated at the start of the current, and α2 at the end? I'm just wondering because my book does it this way and vice-versa, so I'm not entirely...
Experience tells me it is, but my instinct tells me it shouldn't be.
If you place 2 leads of a dc source into water,
how does the charge get from one end to the other?
I can see how it would work with salt water, with the disassociated ions carrying the charge, but that doesn't really have...
Homework Statement
We know that free charges inside a conductor will eventually move to the conductor surface. Consider a free charge initially placed inside a conductor at t=0. Show that the free charge density \rho_f will dissolve exponentially with time. Express the characteristic time...
Homework Statement
http://i258.photobucket.com/albums/hh258/Plutoniummatt/Untitled-1-2.jpg
Homework Equations
Pwr Ref Coeff:
(Z'-Z)/(Z'+Z) all squared
I maybe made a mistake but i can't spot it. And its bugging me
I did square the whole thing afterward for the power...but...
i am reposting this question , earlier it had been deleted assuming it to be a "HOMEWORK QUESTION" ,
well my question is ,
can we define a dielectric constant for a conductor ?? is it conceptually meaningful?? if yes then why and what is it?
Hi.
I'm doing an experiment and I'm kinda stuck.
I know that a current produces a magnetic field. In this experiment there is a current carrying wire (copper) and a permanent magnet suspended above it. Deflection is being measured as the current is varied.
I know that both magnetic...
Homework Statement
An isolated conductor of thickness 'a' is placed between the plates of a parallel plate capacitor. Find the capacitance
Homework Equations
C = A/(4*pi*d)
The Attempt at a Solution
C1 = A/(4*pi*((d-a)/2))
C2 = A/(4*pi*((d-a)/2))
1/C = 1/C1 + 1/C2...
There is this problem of a conducting rod being in a uniform magnetic field. When the rod is being moved, some answers that there will not be an induced emf as there is no change in magnetic flux linkage but some answer that there is.
Anyone can clarify?
Thanks.
I'm only midway to finish my introduction to electromagnetism (level around Resnick-Halliday) so I understand the concepts I will talk about, but I never derived them.
For example, in the case of a spherical (not empty) conductor or any other solid conductor. If we charge it with extra...
Homework Statement
First part of the question:
A rectangular loop is placed near a long straight conductor.
Conductor is oriented vertically to the XY plain at the origin the loop is contained within the YZ plain.
Current passing through conductor.
I = 19 Ampere
dimensions of the loop...
Homework Statement
Let's say I have :
Spherical conductor of radius=x;
Spherical conductor has a inner cubic cavity of side = b;
inside the cubic cavity we have a charge = y;
the surface of the sphere has a charge density = z;
I need to calculate the electric field at some point g, where...
I was taught in my Eletricmagnetics Lessons that the density of electric charge is higher near the surface with big curvature and lower near the flat surface.
Why does the density of electric charge has something to do with the surface curvature?
Is this because such a system has the minimal...
A few questions about electric field here:
1. Why do charges have to be on the outer surface of the conductor?
2. Why no charge on the inner surface of a hollow conductor?
3. If charges cannot be inside the conductor, how come the electric potential is constant throughout the conductor when...
Homework Statement
For the configuration shown in the figure below, suppose that a = 6.10 cm, b = 21.6 cm, and c = 26.6 cm. Furthermore, suppose that the electric field at a point 11.5 cm from the center is 3.37x10^3 N/C radially inward, while the electric field at a point 58.6 cm from the...
Homework Statement
An isolated capacitor with capacitance C = 1 µF has a charge Q = 22 µC on its plates.
Now a conductor is inserted into the capacitor. The thickness of the conductor is 1/3 the thickness of the capacitor and is centered in between the plates of the capacitor.
What is...
I noticed a couple of similar threads, but I thought it might be better to start a new one for clarity.
Imagine a simple DC circuit with a static (time invariant) source of potential and a closed circuit with a simple conductor. If you were to trace the potential from the negative terminal...
Homework Statement
This is one of those problems with a U-Shaped Conductor, but this time it is at an angle and the Earth's Magnetic Field is perpindicular to the plane of it. The rails are 10m apart and the conducting rod weights 10 kg. No friction on the ramps, and the only resistance...
Homework Statement
A copper conductor with a cross-section of A and a length of is connected to a battery with a electromotive force of U. The resistance of the conductor is R, and the internal resistance of the battery is negligible.
U = 220 V
l = 10 m
A = 10 mm2
R = 0.01695 \Omega...
In this problem we assume that the photon mass is m > 0. We take a conducting sphere of radius R and put a charge of Q on it. Some fraction of the charge will then reside at the surface and a fraction will move into the bulk. Evaluate the volume charge density in the bulk.
I was shocked to...
friends,
in lightining conductor, a metal plate with number of spikes is connected to the top end of the conductor and kept at the top of the building.
when a negatively charged cloud passes over the building , positive charge is induced on the pointed conductor. the positive charge ionise...
friends,
there is no charge inside a conductor or to put in a better way " why electric charge resides only on the outer surface of the conductor"
thanks in advance
I found this sentence in my textbook very confusing:
"...where k is constant of
proportionality. If we follow SI units, the value of k is 1."
Thus in
SI units, F=kILBsin<theta>=ILBsin<theta>
Why is the value of k taken as 1 only because we're following the SI units?
Homework Statement
A 20cm wire carrying a current of 10A is placed in a uniform
magnetic field of 0.3T. If the wire makes an angle of 40 degrees with
the direction of magnetic field, find the force acting on the wire.
Homework Equations
F=LIB sin<theta>
The Attempt at a...