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.

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2answers
119 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
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1answer
127 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 ...
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1answer
52 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 ...
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3answers
87 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 ...
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2answers
77 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
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1answer
44 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?
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2answers
76 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 ...
0
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1answer
40 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?
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2answers
80 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
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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
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1answer
126 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
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2answers
169 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
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2answers
54 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
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3answers
93 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 ...
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3answers
626 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
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2answers
161 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 ...
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0answers
24 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 ...
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0answers
49 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
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1answer
39 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
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1answer
36 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 ...
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0answers
262 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 ...
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2answers
197 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?
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2answers
64 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 ...
1
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1answer
49 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
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1answer
31 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 ...
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1answer
90 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 ...
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2answers
59 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
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1answer
48 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? ...
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1answer
105 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
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4answers
696 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
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1answer
364 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
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1answer
36 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
131 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
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1answer
206 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 ...
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0answers
45 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
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2answers
82 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
178 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
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1answer
37 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
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1answer
178 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
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1answer
40 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 ...
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1answer
67 views

Showing that the exterior surface charge density of two parallel plates with thickness are equal

I have some problems with the next exercise. It states: Two infinite conducting parallel plates I and II, with thickness $t_1$ and $t_2$ respectively are separated by a distance $L$ from its nearer ...
1
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1answer
56 views

Creation of electric field inside a conductor

My book says that as soon as the two ends of a conducting wire touches the two terminals of a battery, it generates an electric field inside the conductor. Why?
0
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1answer
209 views

Difference between bound and free charge/current in a perfect conductor

For the case of charge, it seems clear that in a perfect conductor the free charge refers to the excess charge that has been dumped into the conductor, while the bound charge refers to the charge that ...
6
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4answers
569 views

Can a positively charged conductor have negative surface charge density somewhere?

This is a simple question that occurred to me while thinking about electrostatics. Let's consider a positively charged isolated conductor in equilibrium. In general, the surface charge density varies ...
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2answers
41 views

Magnetic force between two long conductive wires with current

I was asked to calculate the total magnetic force between two long conductive wires with current on them, flowing in the same direction. I used the formula F$_1$=$μ_o\frac {I_1I_2l}{2πd}$ and got a ...
0
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1answer
41 views

Direction of magnetic field lines around a conducting wire

By way of the first uploaded picture I was taught that magnetic field-lines around a long conducting wire with a current are shaped like concentric circles around the wire. However, a few pages ...
0
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1answer
54 views

Is diamond able to conduct electricity given 5.5 eV of energy? How do we then identify insulators and semiconductors?

I have learnt that the band gap for diamond, an insulator, is $5.5\:\rm eV$. Does this mean that diamond is able to conduct electricity if we give it this immense amount of energy (let's assume we do ...
2
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1answer
230 views

Reason for gold being the most malleable and ductile of metals

I understand how fcc structure enables plastic deformation in metals, but why is gold, in particular, the most malleable and ductile of fcc metals? Is there something about the electronic structure ...
0
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1answer
586 views

What happens to potential when a charged body is placed next to an uncharged conductor?

I know that the potential of the charged body decreases due to induction however I feel as though I need a more in depth answer. Why does induction cause the potential of the charged body to decrease ...
1
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1answer
59 views

derivative of the electric field along the normal to the surface near the conductor

how to derive the formula approves the derivative of the electric field along the normal to the surface near the conductor is inversely proportional to the principal radii of curvature? $\frac{\...