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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673 views

Gravitational doubt [duplicate]

If we can shield a charge from electrical forces by putting it inside a hollow conductor. Can we shield a body from gravitational influence of nearby matter by putting it inside a hollow sphere or by ...
12k views

Why don't you get electrocuted when you jump and touch an electric fence?

I've read that you won't get electrocuted if you jump and touch an electric fence because you aren't closing the circuit with the ground. Which is also why birds don't get electrocuted when they're ...
2k views

Filament lamp: Negative part of I/V characteristic?

I don't understand the negative part of the graph. It shows that the resistance is decreasing as the voltage goes from negative towards 0. What does a negative voltage mean and why does the graph ...
1k views

Is there no electric field inside a conductor?

I came across this statement while studying electric currents and I am confused: "There is no electric field inside a conductor. Hence no current can flow through it". Is there a fallacy in this ...
108 views

How fast does an electron move?

I've been reading this website: www.physics.wayne.edu/~apetrov/PHY2140/Lecture8.pdf to learn how fast an electron moves in a circuit. On page #8, #9 and #10 It says to take the Cross-sectional Area ...
87 views

Question on direction of electric field

My physics textbook (1st year university course on Electrostatics) mentions that when looking at a positively charged metal disc from the side, the electric field is located perpendicular to the ...
556 views

Image charge method to find electric field [closed]

The following is a question from my tutorial on boundary value problems and image charge method- A point charge +q is placed at (0, 0, d) above a grounded infinite conducting plane defined by z = 0. ...
867 views

Migration of an ion in a non-conductive medium

Someone asked me why, when performing DNA electrophoresis we need to put the gel inside a conducting buffer. Couldn't we just run it in distilled water? My answer was that if we had distilled water ...
289 views

Electric field inside a conductor

I would like to clear things up: How exactly the electric field inside a conductor is zero? Let a really "powerful" electric field be outside of it, how can the "few" charges in a conductor balance ...
49 views

Why are 'low frequency' EM waves attenuated by a single layer of kitchen foil?

Can someone explain why my am radio doesn't work when covered by a layer of foil that is less than one 'skin depth' at the appropriate frequency? According to wikipedia and other websites on the ...
69 views

Is there a theory of electrostatics in the presence of conductors with finite conductivity?

A substantial part of my university EM course was devoted to the study of conductors in the presence of static electric fields. Poisson and Laplace equations were covered, along with the uniqueness ...
1k views

Can you conduct electricity through a banana peel?

While grabbing a banana for breakfast today I got zapped due to static electricity building up while I was moving on my chair, but the conductor I was grabbing was said banana. Is it possible to ...
543 views

Does an electron physically flow? [duplicate]

In a DC current in a conductive wire, is it more accurate to think of one electron wiggling its way through a sea of electrons... or to think of one electron bumping into another, which bumps into ...
344 views

How can the free charges of a conductor redistribute to the surface?

I have studied that if I put a conductor (perfect or non-perfect) at rest in a place where there is an electrostatic field, the charges of the conductor will distribute so that negative charges will ...
221 views

How to interpret Ohm's law?

I just started learning about Ohm's law and the textbook defines it as: Provided the temperature is constant, then for an Ohmic conductor the current through it is directly proportional to the ...
13k views

What is the dielectric constant of a pure conductor?

Dielectric constant is the ratio of permittivity of a medium to the permittivity of free space. How to find dielectric constant of a conductor?
592 views

E field of parallel plates with metal inside

I was asked to determine the electric field in the spaces between the copper bar and the plates. The voltage across the plates was 30 V, so naturally I’d use $E=\Delta V/d$ to determine the field. ...
613 views

Why does the superposition principle work in method of images?

Okay, let there be a conducting sphere having radius $a$ initially charged with $Q$ & insulated. Now, $q$ is brought in front of the conductor at $y$ from the center. Now, Jackson in his book ...
160 views

Does charge distribute itself uniformly on a conductor?

An excerpt from a beginning E&M book [...] In other words, the surface of a conductor is an equipotential surface under static conditions. [...] Summarizing the boundary conditions at the ...
26 views

Electric field inside a conductor with an opening

Assume that we have a charged conductor of any shape but it has an opening so that we can get inside the conductor through that opening . Will the electric field be zero inside that conductor ? I ...
184 views

Which type of conductors don't follow Ohm's law? [closed]

Which type of conductors don't follow Ohm's law? I know that semiconductors and superconductors don't follow them, but why? And what about ideal conductors. What are they? Do they follow ohm's law? ...
75 views

1k 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 ...
65 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 ...
176 views

How is voltage proportional to current?

The question came up in another forum - "What causes current to flow". Many knowledgeable people explained that what causes the flow of charge are electric field forces or Coulomb forces. If there is ...
151 views

Charge Distribution on Conductor - Uniform or Not?

Consider a hollow conducting spherical shell S1 inside an irregularly shaped conducting wall S2 (in the figure). The sphere S1 is somehow given a charge +Q. Will the charge distribution on S1 be ...
350 views

Why does charge distribute itself uniformly only on the surface of spherical conductors?

I understand why charge does not distribute itself uniformly on the surface of a conductor of any other shape. I do not understand why charge distributes itself uniformly only on the surface of a ...
62 views

Current in a conductor

In electrostatic shielding, we have read that the charged particles in a conductor experience no force. In the current carrying conductor, electric field is applied across its ends and the ...
271 views

The consequence of electric field lines not being perpendicular to conductor (assuming a spherical one)

The following statement is from University Physics (chapter "Electric Potential"): "In particular, at any point just inside the surface the component of E vector tangent to the surface is zero. It ...
169 views

Electric current in anisotropic media

I'm trying to model a bulk metal with anisotropic electrical conductivity such as graphite. I want to run a stationary current through the material and I am using the finite volume method to do this. ...
401 views

Magnetic field in perfect conductor : how to decide the “initial value” as $B=cste$

In a superconductor, we have no magnetic field because of Meissner effect. In a perfect conductor, as $\vec{E}=\vec{0}$, we have $\frac{\partial \vec{B}}{\partial t}=\vec{0}$. Thus the magnetic ...
137 views

Why are hollow conductors used for signals of a certain frequency?

So this question is really about skin depth. I have been introduced to the skin depth by a simple model (simple equation for electrons in a metal with a damping term) of polarisability for a metal. In ...
1k views

Is it safe for a man standing inside a Faraday cage to touch it from inside

Will a man get electrocuted if he touches a Faraday cage from inside when a high potential difference is developed between a Faraday cage and some other source? If yes then how a person wearing ...
We have a conductive spherical shell and a point charge $q$ near it. And Is the field inside the spherical shell (where is in fact not inside of the conductor) zero?