Conductor Definition and 820 Threads

Homework Statement three concentric hollow conducting shells are there . inner most is given charge +q , outer most is given charge -q and middle one is earthed , then find charge appearing on all the surfaces ? Homework Equations v= k q / r , E=k q /r2 The Attempt at a Solution no...

The lines of flux of the magnet possesses the following properties: 1)Forms closed loop 2)Starts from N-pole and closes at S-pole 3)Do not intersect each other 4)Parallel line and same direction repels each other 5)Parallel line and opposite direction attract each other So...

In an irregular shaped charged conductor will the electric field E at all points within the conductor be zero? If yes, then how?

I know there must be something wrong with the following derivation based on Maxwell's equations but could not figure out what is wrong. The derivation deals with continuity of current and free charge in a conductor in general. Continuity of current says that, \nabla\cdot...

Hello, I was wondering if anyone could tell me of an easily available (to a primary school teacher) solid material that conducts electricity, but noticeably poorly, so that it can be demonstrated and hopefully performed by 9 year olds. To be exact, I want a solid material that can be...

Homework Statement There are 2 parallel plates of unknown area. The area between the 2 plates is completely filled with 150 kg of water. The capacitance is .3 mirofaradays. K of water is 120 and had density of 1000 kg/m^3. Also Eo = 9.1 x 10^-12 C^2/(NxM^2). Determine the distance between...

imagine there is a positive pt charge somewhere in space. so the E field due to this pt charge, falls off with distance. now, i place a conducting rod parallel to the field some distance away, such that one end of the rod is at V_A and another end is V_B (where V_A > V_B) we also know...

Consider a hollow cylindrical conductor in vacuum with its axis aligned with the z-axis, and with a positive surface charge density σ. The direction of the electric field is radial and its magnitude E is only a function of the distance r from the z-axis, E = E(r). Use Gauss' law to obtain...

Homework Statement A current of constant density, J0, flows through a very long cylindrical conducting shell with inner radius a and outer radius b. What is the magnetic field in the regions r < a, a < r < b, and r > b? (Use any variable or symbol stated above along with the following as...

Homework Statement When we keep a circular copper (ohmic) conductor at a constant temperature T_1, thermal energy is produced along it at a rate P_1 and the magnetic field at its center has magnitude B_1. Then, we heat the conductor to a higher constant temperature T_2 (i.e. T_2>T_1). At...

If we are given a metallic conductor in a given Temperature(Room temperature here), Area of cross section A, is there an upper limit to the strength of the current through such a conductor due to the upper limit for drift velocity(v)?? I=nAve e=electron charge n=electron density

Hello, I was curious, why is that for an electric field to be zero, the conductor must be in static equilibrium, but when charges are moving, the electric field is nonzero?

Homework Statement Consider a point charge q > 0 which is surrounded by a hollow metal sphere (uncharged) with inner radius R1 and outer radius R2. Use Gauss Law to determine the electric field E=E(r)er in the following regions: (i) 0 < r < R1 (ii) R1 < r < R2 (iii) r > R2 Homework...

Homework Statement A point charge q is at the center of an uncharged spherical conducting shell, of inner radius a and outer radius b. How much work would it take to move the charge out to innity? (find the minimum work needed. Assume charge can take out through a tiny hole drilled in...

Is there some material that could withstand relatively high voltages before it starts to conduct electrons,but in the same time a good hole conductor? Could such material be obtained by doping some dielectric similar to SiO2?

Understanding the physics of "induced charge" over a perfect conductor When we put a perfect conductor, let's say a sphere inside an external electric field, there will be a surface charge distribution different from 0 even though the sphere is electrically neutral. I don't really understand...

I was wondering, what is the distinction made with problems involving either conductors or insulators with electrostatic problems. Is it that the electric field in an insulator doesn't have to be zero, whereas the electric field in a conductor is always 0?

Homework Statement A thin, square, conducting plate 50.0 cm on a side lies in the xy plane. A total charge of 4.00 x 10-8 C is placed on the plate. Find (a) the charge density on each face of the plate, (b) the electric field just above the plate, and (c) the electric field just below the...

Clarification about a conductor as an equipotential... Homework Statement This is not a specific problem, but a general question I have. In Griffiths 2.5 (pg. 97 for Third Edition), it states that "A conductor is an equipotential. For if a and b are any two points within (or at the...

Homework Statement How do the charges distribute when I have a spherical conductor centered cavity with a point charge not in center inside the cavity? See image: Homework Equations N/AThe Attempt at a Solution I would guess solution 1, but my tutor says it's 4, and I just can't believe him...

Which materials exhibit good electron and hole conductivity in the same time? And which of them are cheap and available?

Hi Everyone, I'm working on some inductance calculations and was wondering if anyone knows of any formulas (or methods) to determine the inductance of a straight piece of copper pipe, if the ID, wall thickness, and length are known? The closest thing I have found so far was the inductance of...

I've been trying to get my head arround this problem for several days now, and while I deemed it relatively simple at first it turns out that I can't figure out the BCs on a conductor, to which we apply a potential U. In the simplified version of the problem, there is a rectangular conductor...

Homework Statement Consider a hollow spherical conductor with total charge +5e. The outer and inner radii are a and b, respectively. (a) Calculate the charge on the sphere's inner and outer surfaces if a charge of -3e is placed at the center of the sphere. (Use the following as...

Homework Statement A charge q is a distance d from the centre of an earthed conducting sphere of radius a (d > a). Given that the image charge for this system is is q1 located a distance b from the centre of the sphere where ##q_1 = -\frac{aq}{d},\,\,b = \frac{a^2}{d}##, calculate an...

How did Walther Lewin arrive to the result W = x*(σ/2ε0) in 3:00-4:00? Ie, why did he take the average? I don't get it entirely.

(I'd like to preface this with the warning that the following question may be a very dumb one.) My understanding is that current density (or flux) \vec{J} = \vec{J}(x, y, z) is the rate of flow of charge (or the current) per unit area. (Units of \frac{\text{C/s}}{\text{cm}^2} .) Say...

Hello pf, Electrons are the charge carriers in metal conductor. while explaining about the fact the fact that electric field inside a conductor is zero, there is a depiction showing charge moves to surface (+ve and -ve charges to extremes of metal conductor surface) in emt books...

Homework Statement A hollow metal sphere has 7cm and 9cm inner and outer radii, respectively. The surface charge density on the inside surface is - 300nC/m^2</units> . The surface charge density on the exterior surface is + 300nC/m^2</units> . What is the strength of the Electric Field at...

Homework Statement You are inside a large, hollow conductor that is isolated from the ground. There is a large charge on the conductor. If you touch the inside of it, will you be harmed? What if you had a charge with opposite sign of that on the conductor? Homework Equations N/A...

Hello, this is my first post here, so hopefully I do this in the right way... Homework Statement A hollow spherical conductor carries a net charge of 21.5 μC. The radius of the inner hollow is 5.2 cm and thee full radius of the sphere is 7.8 cm. At the center of the sphere, in the...

Dear all, I have a question on the derivation of the drift velocity in a conductor, and was wondering if somebody could help me with it: drift velocity is the average velocity which a free charge moving in a conductor has due to the influence of an electric field applied to the conductor. In...

i want to compare force on current carrying conductor , 1)placed in air surrounded by magnetic field 2)placed in the cylindrical cavity(without air gap but some electrical insulation) which is placed in magnetic field. please give me practically calculated answers with calculations.

I was watching a video on the internet about charge distributions over solid conductors. The solid conductor was heart shaped which was positively charged. The lecturer in the video said that when you touched this conductor, the charge would distribute itself non-uniformly over the surface of...

If you have a bar conductor that's moving perpendicular to a magnetic field, the magnetic force would bring all the electrons to one side of the conductor, leaving one end positive and the other end negative. If you cut the conductor in half while it is moving, will one end be positively...

Say you had a rectangular piece of conductor perfectly balanced on a central pivot point. Around it, you put something that causes an electric field throughout the region. On one end of the balanced piece, atomic cores get exposed as the electron sea rushes to the opposite side via induction...

Homework Statement OK first, I didn't know where to post this since it is and is not homework,anyways, posting here would be safest. Now, the attached scan is a proof from my (not so trustworthy) textbook and I have some doubts in it. The first doubt is in statement S1 : Every element...

Many sources on the web claim that when moving a conductor through a magnetic field, an emf is produced. However, some sources claim, that the intensity of the magnetic field also needs to change in order to produce a voltage over the conductor, for example...

i have read that if we place an unit positive electric charge in an electric field the path in which it moves is the electric lines of force of that electric field . is it true ? and again that the lines of force doesn't make a closed curve . is that also true ? if yes then if we can make a...

I have read that the electric field from a point charge fall off as 1/(r*r) since it is analogous to variation of intensity of radation from source (whose geometric proof depends on solid-angle), similarily is there any geometric explanation why magnetic field in the stated case fall off as...

Hello , What is the electric field inside a hollow rectangular conductor of length ( L ) ?

Hi there. If I wanted to calculate the radiation vector (in z > 0) produced by a short dipole with uniform current Io (+z direction) on a infinite perfect electric conductor (plane z=0), I'd have to apply the images method. So I'd have to calculate the radiation vector produced by two short...

When an electromagnetic wave hits a conductor the transmitted part of the wave is damped considerably. I want to know if anyone can explain physically why the field is attentuated inside the conductor - i.e. what happens. I know the basic properties of a conductor: - Electrons free to roam -...

I understand that if two points are inside a conductor they're at the same potential. I also understand that if two points lie on the surface of the conductor they're at the same potential. If point a lies on the surface of a conductor and point b lies inside is there still zero potential...

Homework Statement A ground spherical conductor of radius a lies at the center of a uniform spherical sheet of charge QB and radius b. a) How much charge is induce on the conductor's surface? Ans(-QBa/b) Evaluate V(r) at position between the conductor and the sheet and outside the sheet...

I don't really understand how electromagnetic waves in wires are created. Sure you can see from the Maxwell equations that the fields satisfy the wave equation. But if you plug some cables onto a battery isn't the situation more or less static. I mean the electric field from the battery has...

Dear Physics Forums readers Let a two dimensional rectangle R1 carry a surface charge \sigma and be placed next to another rectangle R2 of the same shape made from metal (i.e. a conductor). What does the electric field look like close to the second rectangle? My intuition would tell me, the...

Homework Statement A conductor, maintained at a potential V, contains a spherical cavity of radius R. A point charge q is placed at a distance a ( a < R)from the center of the cavity. Find the potential of the electric field in the cavity . Homework Equations I was considering using...

If you place a conductor in an external E-field the charges inside it will move so as to cancel off the field making the field inside the conductor zero. My question is: Is this also true if you place some net charge on a conductor? Will the field inside it then still be zero? The net charge...

Hi. Practical situation. If I have 0.25W of constant Joule loss around a small piece of copper electric conductor, then I would like to find out how much time until a small piece of "Something" (let's say 100mg at 1 kJ/kg*K) around the conductor heats up to 200°C. From my calculations...