Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [conductors]

For questions about materials which allow the flow of an electric charge (electrical conductors) or the transfer of heat (thermal conductors) through them.

0
votes
1answer
14 views

Does a conductor actively lose charge during electrical breakdown?

Electrical breakdown occurs when the potential difference between a conductor and the medium surrounding exceeds the breakdown voltage. In such scenario, the electric field at a boundary point is ...
0
votes
1answer
28 views

How can the surface of a conducting shell be equipotential when a charge is introduced inside the cavity?

Here is the confusion. Take a spherical conducting shell of a certain thickness. When a postive charge is introduced into the shell the inside surface collects negative charges and the outter ...
4
votes
2answers
44 views

Why is the electric field between two conducting parallel plates not double what it actually is? [duplicate]

According to here: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elesht.html We can treat two parallel plates as being a single conductor which has an electric field of $\frac{\sigma}{\...
0
votes
0answers
29 views

Does a superconductor conduct electricity at room temperature?

I know you need to cool a superconductor below a certain temperature for it to exhibit superconductivity, but do superconductors, specifically YBCO superconductors, conduct electricity normally at ...
1
vote
1answer
36 views

How to (hypothetically) calculate $\tau$, the mean free time?

Referring to the Drude Model, I've seen a lot of excellent questions on whether $\tau$ should be thought of as the "average time between collisions" or the "average time until the next collision", and ...
-2
votes
0answers
46 views

Difference in formulae

Why is there a difference of opinion in these books? Could you please provide the rigorous derivation which the author states in the second image? And why isn't the formulae same?
0
votes
1answer
28 views

A Conducting Disc

A conducting disc is given a charge Q. As the disc is conducting it must be equipotential and hence the charge distribution will not be uniform. From what I know the charge will have a tendency to ...
0
votes
1answer
11 views

Electric potential inside a solid conducting sphere, next to other charges

The way I initially justified the potential inside a charged conductor to be $\frac{kQ}{R}\ for\ \ 0\le r\ <R$ was that from Gaus's law, you could determine that when you were a distance $r$ away ...
0
votes
1answer
17 views

Force between two point charges separated entirely by a conductor

The relative permittivity and hence absolute permittivity of a conductor is infinity. Now coulomb force between two point charges is inversely proportional to the permittivity of the medium between ...
1
vote
1answer
90 views

Induced charge in a conductor

My question here is based on the following question in Physics for Scientists and Engineers (3rd edition) by Randall Knight: An electroscope is positively charged by touching it with a positive ...
3
votes
2answers
63 views

What will happen when two conducting spheres are touched?

Suppose I have a conducting sphere with a charge of $$1.6 * 10^{-19} C. $$ What will happen when i touch this sphere with an identical neutral sphere? On which sphere will the charge reside?
0
votes
1answer
59 views

Existence of Electric field around a current carrying conductor? [duplicate]

A magnetic field could not be induced unless there is a time varying electric flux associated with the amperial loop under consideration. But a well known field exists around a current carrying ...
1
vote
1answer
48 views

Relativistic effect in a current carrying wire

In many places I read that in the rest frame of a current carrying wire (electrons in motion), the spacing between the positive ions is length contracted and equal to the length contracted spacing ...
0
votes
3answers
73 views

Why doesn't the flow electrons occur in a broken circuit?

Take a battery and connect a small led bulb across it with the help of two wires. The bulb will glow, but if I cut a small piece of wire from any part of the connecting wires,the circuit will not work ...
1
vote
2answers
62 views

Electric Field Inside of a Conductor [duplicate]

I have seen many explanations for why the net electric field inside of a conductor is zero (assuming only electrical forces are acting on the particles inside of it). These explanations typically say ...
-1
votes
1answer
41 views

How electric current is defined in a metal wire?

How current is defined if in a metal wire both positive and negative charge exist? Isn't the total charge/time 0?
3
votes
2answers
51 views

Why some forces follow superposition principle?

Let there be a system of $n$ source charges and a test charge $Q$. When we say superposition applies to electrostatic force, we conclude that the interaction between a given source charge and the test ...
-1
votes
1answer
33 views

Relation between Temperature and heat current

This problem: I was able to solve it doing this: But I think i have nowhere " exploited " the equivalence given above. How can this be used in this problem?
1
vote
2answers
26 views

The image charge inside the conducting sphere without producing any electric field [closed]

In the method of images for a grounded conducting sphere, we calculate the position of image charge at $$\frac{R^2}{r}$$, due to which there should be an electric field inside the conducting sphere ...
0
votes
0answers
32 views

Do conductors reflect Wifi signals? If so why?

I know electric field can't pass through conductors, but I have seen people surround their wifi router by soda can (not entirely) for better signal strength. I want to know what really happens there.
0
votes
1answer
70 views

Charge $Q$ in cavity inside conductor

A point charge Q is inside a cavity in an uncharged conductor. Is the force on Q necessarily zero? The explanation in the answer goes as No. For example, if it is very close to the wall, it will ...
5
votes
2answers
142 views

How far do electrons actually move along a conductor under an alternating current?

This is more or less a curiosity question. But I have had really good luck with stack exchange so far. If I can expand on my question a little bit - it may not be super important, but I know under say ...
2
votes
2answers
49 views

Is it possible to become electrocuted even if using a Faraday suit on a high-voltage line?

I am a writer. I'm working on a novel (yes, fiction) but want to do my best to present a passage as accurately as possible. The crux of the question is whether or not someone using a Faraday suit ...
2
votes
3answers
87 views

Do real electrons solve the Thomson Problem?

The question of how $N$ electrons (seen as point charges) on a conducting sphere will arrange themselves in the electrostatic final state was first posed by J.J. Thomson in 1904--hence, aka the ...
0
votes
3answers
158 views

Non-ohmic conductors

Non ohmic conductors are said to be the conductors that do not obey Ohm's Law. The V-I graph for them is not a straight line unlike ideal ohmic conductors. According to me Ohm's Law states: The ...
0
votes
2answers
87 views

Charge Distribution on a perfectly conducting hollow shell

As shown in the figure, I have a hollow shell which contains a charge at its centre and another charge is placed outside the shell (some distance apart). I know that the situation this figure depicts ...
0
votes
0answers
20 views

Why is there an accumulation of charges at the junction of 2 rods of different metals joined together?

Let two similar rods of different metals ( say copper and iron ) are joined together and some current is let to flow . Is there a charge accumulation at the junction? 1. If so what is the cause of it ...
0
votes
0answers
46 views

Paradox in conservation of energy

Let us assume there is a constant electric field in an interested region (finite volume)and a non-conducting object is thrown into it with speed $v$ and now take the second scenario with the same ...
0
votes
1answer
34 views

How to compute the self-capacitance of a conductive shape?

(Depending on the answers given, this question might be better suited for Math.SE, but I don't think so.) I recently learnt about the notion of self-capacitance of a conductive shape, which now seems ...
2
votes
1answer
35 views

Is there an magnetic field around ideal conductor?

Im gonna dive straight to the point: If you run some current through, say, copper wire you will get a magnetic field around it; that is how the gauss guns work. My questions are: 1) Is it possible ...
0
votes
0answers
95 views

Capacitance of spherical capacitor when inner sphere is earthed

Consider the following derivation: (Source: http://www.ncert.nic.in/html/learning_basket/electricity/electricity/electrostatics/inner_sphere.htm) If a charge of $+Q$ coulombs is given to the outer ...
1
vote
2answers
103 views

Metal rod in an electric field

A metallic rod is placed in a uniform electric field. Why is an electric field induced in the opposite direction?
1
vote
2answers
62 views

Is it the current which create magnetic field, or vice versa, or both?

Talking about stationary magnetic field, it is said that if a conductor rotates inside the field, a current is induced. Also, I read that current (moving charges) generate magnetic field, too. How are ...
0
votes
1answer
42 views

On the electric field created by a conductor

The electric field created by a conductor at a point $M$ extremely close to it is $\vec{E}=\vec{E_1}+\vec{E_2}$ where $\vec{E_1}$ is the electric field created by such a tiny bit of the conductor that ...
0
votes
1answer
27 views

How do I solve for the voltage on a geometry that has varying thickness of a conductive metal?

I currently have a 3D geometry which is made from an isotropic material. In my case this material is simply a highly conductive metal. We can think of this geometry almost as a thin film with slightly ...
-1
votes
1answer
69 views

Relative Permittivity in a “Good Conductor”

I have a question in which I need to show that sea water is effectively a "good conductor", when considering the propagation of radio waves of frequency $< 10^9$. We're given that the conductivity ...
1
vote
2answers
57 views

What is the voltage in electrical circuits?

I understand what the voltage is and I realize that the battery makes an electric field due to the accumulation of the charges in the anode and cathode this electric field causes electric potential ...
0
votes
1answer
45 views

Why does charge 'stick' to the Gaussian surface?

I'm currently studying Gauss's Law and interaction of the charge with different Gaussian surfaces etc. But here's something that I couldn't understand. Why does a charge 'stick' to a Gaussian surface? ...
0
votes
1answer
82 views

How is the $E$-field getting canceled between outer and inner surface of a neutral conducting spherical shell?

I am reading Purcell's E&M book and in one of the example questions, it shows that there is no E field between outer and inner surface after a a point charge is located at an arbitrary position ...
0
votes
3answers
289 views

Electric field due to uniformly charged infinite plane sheet

For getting the electric field in this case we use the Gauss's law. we get the equation $$ 2EA = pA/\epsilon_0 $$ here $E$ is electric field, $A$ is the cross sectional area, $p$ is the uniform ...
0
votes
1answer
227 views

Point charge inside hollow conducting sphere [closed]

Above there is a 2D pic of this problem. $S$ is a conducting sphere with no charge. I am considering the electrostatics case. It is a hollow sphere: inside its cavity lies a point charge $q$,...
1
vote
1answer
31 views

How do I experimentally measure the resistance from using dielectric grease on battery posts?

The internet gives lots of contradicting advise about greasing or not greasing car battery posts to prevent corrosion. So rather than rely on the internet, I want to perform an experiment so that I ...
0
votes
1answer
101 views

Proof that $\vec{E}$-field is constant inside cylindrical resistor

I am reading a proof that the $\vec{E}$-field is constant inside a cylindrical resistor, and I don't understand one of the steps. It is stated that since the surrounding medium is non-conductive the ...
0
votes
1answer
124 views

Charge accumulation in wire

I came across a question about charge accumulation. It states that if a steady current flows in a wire composed of a copper and iron wire of same area (see fig), will the charge accumulate on the ...
1
vote
0answers
42 views

Gauss's Law about excess charge on conductors, quantum mechanics, and doped semi-conductors [closed]

Does quantum mechanics predict that there is any probability of finding excess charge inside a conductor? I've read an explanation about the distribution of excess charge placed on conductors. The ...
0
votes
2answers
73 views

How does the current become homogeneous within a circuit?

I have two questions: In a given circuit with resistances of different values connected in parallel, there is a different build up of electrons when the power source is turned on. Then, how is the ...
3
votes
2answers
115 views

Charge distribution in the wires and resistor, in a DC circuit

1) How do the electrons in a wire with 0 or negligible resistance arrange themselves in order to make the field in the wire 0? 2) The electric potential drop across a resistor is far more than ...
0
votes
1answer
33 views

Does “charge density” account for all charges, or only negative charges, and do opposite charges cancel each other or add?

if I had 10 electrons and 8 protons in a meter cubed would the charge density be 2 or 10 or 18? I suspect 10, but I don't see why charge density only takes into account the negative charges. another ...
0
votes
1answer
96 views

Coaxial cable with compound dielectric

I'm trying to solve a problem from Reitz and Milford's Foundations of Electromagnetic Theory (3rd ed, problem 4-8), and don't know how to start: A coaxial cable of circular cross section has a ...
1
vote
1answer
38 views

Do charges in a metal group up a little in the middle?

Around the edges of a metal, the density of electrons is higher than the rest of the metal. I think this is because every electron is surrounded by neighbours pushing them away but once you get to the ...