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 nonconducting materials with few mobile charges that support only insignificant electric currents.
Hello! I am a junior undergraduate physics major and I am very confused on how to visualize things in my electrodynamics class. Specifically, I am having issues with dielectrics and spheres with constant potentials etc. I usually notice that I am lost in a class when I can no longer draw out a...
Hi.
I was reading about conductors in electrostatic equilibrium and how it makes sense that they have zero electric field inside the material even when an external charge is brought near. The charge density of the material just rearranges itself to cancel. Then I searched for hollow conductors...
Attached is the subsection of the book I am referring to. The previous section states that the electric field magnitude at any point set up by a charged nonconducting infinite sheet (with uniform charge distribution) is ##E = \frac{\sigma}{2\epsilon_0}##.
Then we move onto the attached...
Here I am going to include the proof provided by my book. It is quite a splendid explanation, though there are a few key points I have yet to fully understand. If the electric force by the electric field on the charge at the surface of the conductor is conservative (which it is), then why is...
Recently, I have been studying some solidstate physics and I came across this ##Ek## diagram online. Here's an image for reference to what I am referring to...
The answer according to the key is C. I thought the answer would be E since the electric field inside a conductor is always zero. Can someone explain why the answer is C?
I for one don't see how ##\sin \theta_t \gt 1## is possible, even when you extend into the complex numbers. Is there even a way to order the complex numbers? Does he mean to say that the magnitude is greater than 1?
Anyway here's my attempt at interpreting what my instructor is trying to say...
What is true is that the field due to the point charge outside of the conductor will not be able to penetrate the shell i.e. there will be no field due to the external point charge anywhere within the conductor nor in the cavity: the field will be **killed off*& by the charges on the outer...
So in my textbook (Introduction to Electrodynamics by Griffiths) it said that inside a conductor, the electric field E would have to zero, since if it wasn't the free charges would move accordingly and create a electric field that cancels the original field. But in a question that soon followed...
Homework Statement
This is the exercise 10.6 from Feynman lectures on Physics 2.
Two coaxial pipes of radii a and b(a<b) are lowered vertically into an oil bath. If a voltage V is applied between the pipes, show that the oil rises a height H.
Show that H=(V^2)(κ1)ε_0/[ln(b/a)ρ(b^2a^2)g]
where...
1. Homework Statement
Hello,
I'm learning electricity and I'm having a few conceptual questions regarding the subject ( especially about neutral objects ) which I'm unsure of the answers and I'd be happy if someone could help me:
1. Is the charge density of a neutral object ( doesn't matter...
I have a question in my book and it’s confusing me a bit. I tried to search online for similar solved problems but couldn’t succeed. So here it goes:
Calculate the induced EMF in a conductor loop when the angle between \vec{A} ~ and~ \vec{B} ~is~ changed ~from ~{0 °}~ to ~{α °} in 1...
The electric field inside a conductor is zero. Or: the internal electric field is equal in magnitude but opposite in direction to the external electric field, so that the net electric field inside the conductor is zero.
Why is this? The part where I am confused is why the magnitude is equal...
Homework Statement
Homework Equations
Emf=B l V V is (velocity)
F=QVB
The Attempt at a Solution
Emf=BLV
Work=QBLV
Force=BLV
how come V=Q/m. its not possible or is it?
In my lab we are working with a Coaxial coil and stainless steel tube, and are aiming to find the mutual Inductance. I've done some looking around and have easily found the Inductance of a Coaxial cable, and for that of Coaxial coils, but am having trouble with a combination of the two.
The...
I'm having trouble seeing how electric potential energy production on a conductor follows conservation of energy.
Let's use the photoelectric effect as an example. A photon with energy E = hν strikes a conductor, ejecting a photoelectron with a maximum kinetic energy of hν  φ. Assuming the...
I’ve looked at the answers given to the previous times this question has been asked, but I still don’t seem to understand how this holds in the case of a closed circuit. Here’s an explanation given before:
“Think of the wire as a horizontal cylinder. If you apply an electric field pointing to...
Hi,
I recently came across the familiar image of a metal sphere in an electric field:
https://i.stack.imgur.com/x58Ia.jpg
I noted how the freecharges on the surface of the sphere align with the electric field lines as opposite charges are attracted.
Then I wondered, 'what if the sphere was...
I know that electric conductivity of metallic conductors increases with decrease in its absolute temperature(kelvin) . But is it the same for electrolytes such as water. Is cold water a better or worse conductor of electricity than warm water at same pressure and concentration.
Homework Statement
A + q = 5 pC charge is uniformly distributed on a nonconducting sphere of radius a= 5 cm , which is placed in the center of a spherical conducting shell of inner radius b = 10 cm and outer radius c = 12 cm. The outer conducting shell is charged with a q charge. Determine...
Why is a sea of electrons present in a conductor?
I read some where that they absorb a energy at normal temperatures and use it to get free electrons , but then why do they absorb energy while insulators don't??
I'm no physicist, but I found this material to be interesting.
Samarium Hexaboride is a crystal that exhibits conductive properties at room temperature and insulating properties when cooled to below minus 223 degrees Celsius.
A layman's article...
Homework Statement
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Homework Equations
V= kq/r.[/B]
The Attempt at a Solution
For 88, I do not really know how to approach it.
For 814 , I think that q2=q1 and q3=q1+q2.
I can now use V=kq/r and then find the equations for r>R3 , r=R3 , R2<r<R3 , r=R2 and R1<r<R2 and...
Homework Statement
[/B]
Two long, coaxial metal cylinders are separated by a material of conductivity sigma and dielectric constant epsilon. The radius of the inner cylinder is a, the radius of outer cylinder is b, and the length of both is L.
Suppose that the inner conductor is held at a...
Hi.
If an electrically neutral, conducting rod is brought close to a (say negatively) charged object with one end, charges will separate due to electrostatic induction roughly as follows:
Let's now connect the rod to the (faraway) ground with a long cable. Does it make a difference whether...
Hi.
I learned that in an ideal conductor in a circuit, the voltage drop is zero. But how does this agree with the basic definition of voltage
$$U_{AB}=\int_A^B \vec{E}\cdot d\vec{s}\enspace ?$$
The electric field inside a conductor only vanishes in static conditions, but in an electric circuit...
Hello !
1. Homework Statement
i study for my exams. here is my current problem:
a nonspecific conductor is connected to an ideal battery (surrounding temperature: 20°C) and reaches a temperature of 24 °C . after cut in half it is again connected to the battery. what temperature does it reach...
So the potential inside a conductor is constant. Does this mean that if there were a conductor, B, inside another conductor, A, the charges of A/B would redistribute such that the electric field inside would be zero (hence constant potential)? This seems logical but a bit too easy?
Also, if it...
I read somewhere that conductors don't really store charge? How can this be correct?
When a conductor is charged by conduction, the electrons spread throughout the surface of the conductor. Doesn't this mean that the capacitor is storing this electricity? What prevents conductors from being...
Homework Statement
Is it possible to introduce local charge on a conductor?
Homework Equations

The Attempt at a Solution
I know that electrons can move freely from atom to atom in the conductor, so if you introduce excess electrons to the conductor, they'll spread out and there won't be a...
Homework Statement
A flat capacitor formed by two square plates of side 0.3 m which are 2 mm apart. Source keeps voltage 250 V on the plates. What current flows between the plates and the source if the condenser is immersing in kerosene at velocity of 5 mm / s? The relative permittivity of...
Hi! I have to build a capacitor out of the following materials: 10 square feet of aluminum foil, 10 square feet of saran wrap (polyvinyl chloride), several sheets of paper, and tape to put it all together. I will only have about 30 minutes to manufacture my design. I have been researching...
bear with me, i know that this question has been asked many time , but i would like a definite answer, now, starting off the external charge density on the outer surface of sphere WILL be uniform by unique solution of Laplace equation and letting the sphere be huge, so, electric field due to...
Homework Statement
Find the potential at the centre and at P of a hollow uncharged conducting spherical shell if a charge q is placed at a distance of 2r from centre of shell.
(r is the radius)
Homework Equations
All the charge induced on the sphere has to reside on the sphere's outer...
If there is a small object with positive charge placed above a metal plate, the object induces a negative charge on the surface of the plate facing the object. Let's call this surface as S1.
(The metal plate is initially uncharged).
But from conservation of charge, the net charge in a metal...
Peierls distortion states that for a 1 dimensional polymer (like polyacyteline) with lattice spacing a they should have a halffilled conduction band, why?
And how does changing the lattice space to 2a cause it to form an energy gap? In my mind it should be the same as the first case...
Assume a conductor in a rectangle shape for simplicity.
Now, if I only choose one side of this rectangle, and apply external electrical field ∑ only to it, what EMF would I create on the conductor? I would simply say ∑, however then I had the following idea, and I started to doubt if I create...
Homework Statement
A conducting sphere of radius a is surrounded by a neutral conducting shell of radius b (b > a).Connections are provided as shown in diagram. Initially, the sphere has a charge Q. The switch S1 is opened and then closed. The switch S2 is then opened and closed. Finally, the...
Homework Statement :[/B]
When a steady current flows through a conductor, the electrons in it move with a certain average 'drift speed'. The drift speed of electrons for a typical copper wire is about 1 mm s1 . How is it then that an electric bulb lights up as soon as we turn the switch on...
In an example in my book, the author poses the following question: Given two large plates
at a distance d from each other with arbitrary charges Q' and Q" (with Q' on the bottom plate
and Q" on the top plate), how are the charges distributed on the plates? The author lists
the following...
Homework Statement
How do I prove that a sphere is a conductor?
Homework Equations
E = kQ/r
The Attempt at a Solution
In my mind, if a sphere is a conductor, the charges formed during induction will move to the surface of the sphere as they can move freely in the conductor, and the same...
Homework Statement
I was looking for some practice problems in my textbook and found this problem that I was just a little stuck on. I drew the diagram from my textbook with the givens of the problem.
Homework Equations
∲E*dA = Q (inside) / ɛ0
The Attempt at a Solution
For r less...
A point charge outside a hollow conducting sphere will produce no field in the hollow interior: the metal shields the interior. But a point charge inside the hollow interior will produce a field outside: the same metal ceases to act as a shield. Why is this?
(In particular, aren’t “inside” and...
The common explanation for the electric field inside a conductor being zero goes something like this:
Suppose a perfect conductor is placed in an electric field, the external field causes the free charges to redistribute in such a way, that the resulting internal field exactly cancels off the...
Homework Statement
I never quite understood the principles of earthing, but I think that the general idea is that if you have an object with excess charge (whether positive or negative), then connecting it to the Earth with a conductor will mean that either the excess electrons flow to the...
Homework Statement
A spherical conductor of radius ##a## carries a charge q and also there is a jelly of constant charge ##rho## per unit volume extending from radius ##a## out to radius ##b##.
I'm looking to see if I got the correct set up for the electric field of this spherical conductor for...