Conductor Definition and 790 Threads

In an infinitely long current carrying wire (assuming zero resistance) say there is a definite current. "Having current in it" means there is a flow of charge in it, which means if positive charge moves in one direction then negative charge moves in opposite direction. As we know that a charge...

Homework Statement v=qEt/m t=time between each collision q=charge on particle m=mass of particle E=electric field Why is this the average velocity/drift speed in a conductor? Homework Equations The Attempt at a Solution Doesn't qEt/m = the final velocity of the...

Homework Statement A Spherical conductor has an Electric field near its surface of 180 volts per inch. How much charge (in Coulombs) is on the sphere ? How many excess electrons are on the sphere? Will the air around the sphere break down and produce an arc ? Homework Equations Well, I...

Hi everybody... I have a simple question for you.. Where can i found the expression of the magnetic field around at the conductor which it has finite lenght? because i always found the megnetic filed in a conductor infinite length .. Sorry for the stupid question... tanks and best regard

Homework Statement The potential of a metal sphere of diameter 2 cm is 10^4 V relative to the ground. a) What is the surface charge density? b) How many electrons were removed from the sphere? c) What is the electric field strength at the surface? Homework Equations The Attempt...

Homework Statement The figure shows a portion of an infinitely long, concentric cable in cross section. The inner conductor carries a charge of 5.1 nC/m and the outer conductor is uncharged. What is the electric field 1.9 cm from the central axis? The permittivity of free space is 8.85419e-12...

Hi, I am in Purcell's E&M book at the section explaining why the field is zero inside a hollow conductor of any shape. The proof given is that the potential function inside the conductor must obey Laplace's equation, and that the boundary of the region (in this case a rectangular metal box) is...

In a question there are two conducting shells of radii a and b (a<b),the outer shell is given a charge Q . And the inner shell is grounded then the potential of that shell was equated to zero and its charge was assumed q. And it resulted in an equation KQ/b + Kq/a = 0 this gave q = -(a/b)Q...

I beg you to understand my poor Eng.. If there is any poor grammar or spelling..please correct me.. While studying MHD with "An Introduction to Magnetohydrodynamics" written by Davidson, I encountered the term 'current density'.. As you know well, empirically, \mathbf{J} = \sigma...

Homework Statement Given an electrical dipole of electrical dipole momentum \vec P = p\hat k, centered in 0\hat i + 0\hat j + 0\hat k, find the potential in all the space, where V(\infty ) = 0. If the dipole is now surrounded by a hollow spherical conductor (initially discharged), find the...

The noise power in a conductor is given by P = k.t.B Does this mean the noise power is independant of the conductor length? Also, does this only apply for a conductor with no resistance? Thnks, Rudi

In the case of a finite conductor rod moving at a constant velocity perpendicularly to a uniform magnetic field, E. Purcell says that the free charges in the rod suffer a force such that they move to an extremity of the rod. When in the final state, he says (at least this is what I understand)...

When finding the angles for the finite length Biot-Savart formula of a filamentary conductor H = I*(cos(α2) - cos(α1))aΦ/(4πρ), is α1 supposed to be calculated at the start of the current, and α2 at the end? I'm just wondering because my book does it this way and vice-versa, so I'm not entirely...

Experience tells me it is, but my instinct tells me it shouldn't be. If you place 2 leads of a dc source into water, how does the charge get from one end to the other? I can see how it would work with salt water, with the disassociated ions carrying the charge, but that doesn't really have...

Homework Statement We know that free charges inside a conductor will eventually move to the conductor surface. Consider a free charge initially placed inside a conductor at t=0. Show that the free charge density \rho_f will dissolve exponentially with time. Express the characteristic time...

Homework Statement http://i258.photobucket.com/albums/hh258/Plutoniummatt/Untitled-1-2.jpg Homework Equations Pwr Ref Coeff: (Z'-Z)/(Z'+Z) all squared I maybe made a mistake but i can't spot it. And its bugging me I did square the whole thing afterward for the power...but...

i am reposting this question , earlier it had been deleted assuming it to be a "HOMEWORK QUESTION" , well my question is , can we define a dielectric constant for a conductor ?? is it conceptually meaningful?? if yes then why and what is it?

Hi. I'm doing an experiment and I'm kinda stuck. I know that a current produces a magnetic field. In this experiment there is a current carrying wire (copper) and a permanent magnet suspended above it. Deflection is being measured as the current is varied. I know that both magnetic...

Homework Statement An isolated conductor of thickness 'a' is placed between the plates of a parallel plate capacitor. Find the capacitance Homework Equations C = A/(4*pi*d) The Attempt at a Solution C1 = A/(4*pi*((d-a)/2)) C2 = A/(4*pi*((d-a)/2)) 1/C = 1/C1 + 1/C2...

There is this problem of a conducting rod being in a uniform magnetic field. When the rod is being moved, some answers that there will not be an induced emf as there is no change in magnetic flux linkage but some answer that there is. Anyone can clarify? Thanks.

I'm only midway to finish my introduction to electromagnetism (level around Resnick-Halliday) so I understand the concepts I will talk about, but I never derived them. For example, in the case of a spherical (not empty) conductor or any other solid conductor. If we charge it with extra...

Homework Statement First part of the question: A rectangular loop is placed near a long straight conductor. Conductor is oriented vertically to the XY plain at the origin the loop is contained within the YZ plain. Current passing through conductor. I = 19 Ampere dimensions of the loop...

Homework Statement Let's say I have : Spherical conductor of radius=x; Spherical conductor has a inner cubic cavity of side = b; inside the cubic cavity we have a charge = y; the surface of the sphere has a charge density = z; I need to calculate the electric field at some point g, where...

I was taught in my Eletricmagnetics Lessons that the density of electric charge is higher near the surface with big curvature and lower near the flat surface. Why does the density of electric charge has something to do with the surface curvature? Is this because such a system has the minimal...

A few questions about electric field here: 1. Why do charges have to be on the outer surface of the conductor? 2. Why no charge on the inner surface of a hollow conductor? 3. If charges cannot be inside the conductor, how come the electric potential is constant throughout the conductor when...

Homework Statement For the configuration shown in the figure below, suppose that a = 6.10 cm, b = 21.6 cm, and c = 26.6 cm. Furthermore, suppose that the electric field at a point 11.5 cm from the center is 3.37x10^3 N/C radially inward, while the electric field at a point 58.6 cm from the...

My teacher said so, but I just don't understand why. Is it because of the free movement of electrons inside the conductor?

Homework Statement An isolated capacitor with capacitance C = 1 µF has a charge Q = 22 µC on its plates. Now a conductor is inserted into the capacitor. The thickness of the conductor is 1/3 the thickness of the capacitor and is centered in between the plates of the capacitor. What is...

I noticed a couple of similar threads, but I thought it might be better to start a new one for clarity. Imagine a simple DC circuit with a static (time invariant) source of potential and a closed circuit with a simple conductor. If you were to trace the potential from the negative terminal...

Homework Statement This is one of those problems with a U-Shaped Conductor, but this time it is at an angle and the Earth's Magnetic Field is perpindicular to the plane of it. The rails are 10m apart and the conducting rod weights 10 kg. No friction on the ramps, and the only resistance...

Does anybody happen to know what readily-available metal is the worst electrical conductor?

Homework Statement A copper conductor with a cross-section of A and a length of is connected to a battery with a electromotive force of U. The resistance of the conductor is R, and the internal resistance of the battery is negligible. U = 220 V l = 10 m A = 10 mm2 R = 0.01695 \Omega...

In this problem we assume that the photon mass is m > 0. We take a conducting sphere of radius R and put a charge of Q on it. Some fraction of the charge will then reside at the surface and a fraction will move into the bulk. Evaluate the volume charge density in the bulk. I was shocked to...

friends, in lightining conductor, a metal plate with number of spikes is connected to the top end of the conductor and kept at the top of the building. when a negatively charged cloud passes over the building , positive charge is induced on the pointed conductor. the positive charge ionise...

friends, there is no charge inside a conductor or to put in a better way " why electric charge resides only on the outer surface of the conductor" thanks in advance

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I found this sentence in my textbook very confusing: "...where k is constant of proportionality. If we follow SI units, the value of k is 1." Thus in SI units, F=kILBsin<theta>=ILBsin<theta> Why is the value of k taken as 1 only because we're following the SI units?

Homework Statement A 20cm wire carrying a current of 10A is placed in a uniform magnetic field of 0.3T. If the wire makes an angle of 40 degrees with the direction of magnetic field, find the force acting on the wire. Homework Equations F=LIB sin<theta> The Attempt at a...

Homework Statement Use Gauss' theorem (and the fact that the line integral of the electric field around a closed loop is zero, if necessary) to prove that a closed, hollow conductor shields its interior from fields due to charges outside. (This is 1.1b in Jackson, and it's not really homework...

Homework Statement Is the relative permittivity (ie.dielectric constant) of a conductor (metal) zero,or,infinity? Prof. Jaiswal in his golden physics (for XII std. CBSE) states that it is "zero". Another author Prof. Mohindroo in his book based on the same XII std. CBSE physics syllabus...

Homework Statement A long, thin conductor carries a current of 8.93 A. At what distance from the conductor is the magnitude of the resulting magnetic field 4.79 × 10−5 T? Answer in units of cm. Homework Equations B= Uo*I*l/(2*pi*d) The Attempt at a Solution i used this...

Two aluminium plates, each 150 x 150mm, were separated by 100mm to create a form of parallel-plate capacitor. A DC voltage of 300 volts was connected across the plates to create a (fairly) linear electric field of approximately 3000 V/m between them. An insulated conductor was bent into a U...

Two aluminium plates, each 150 x 150mm, were separated by 100mm to create a form of parallel-plate capacitor. A DC voltage of 300 volts was connected across the plates to create a (fairly) linear electric field of approximately 3000 V/m between them. An insulated conductor was bent into a U...

Homework Statement What is the magnetic induction at a point on a current carrying conductor itself according to biot -savart law? is it zero, infinity? Homework Equations The Attempt at a Solution

Homework Statement calculate total induced charge on a charged cylinder. where the surface charge density is given by sigma= 2eEo cos(phi) Homework Equations the total induced charge on the cylinder is Integral of (sigma) da can u calculate this integral fo me ... it very...

Homework Statement http://img16.imageshack.us/img16/6503/questiono.jpg Not sure which equations, pretty sure anything goes for find e fields like guass. I'm not even sure of the behavior of the system. Two conducting spheres with a charge on them, the field of each one just be...

Hi, skin depth tells us that an electromagnetic wave is attenuated but when is it reflected? When i aim light on a mirror its clearly reflected. My question is if its at the border ( right when it goes from air to metal) or at some place inside the conductor (if the latter, then how is a...

A metal is held by E.F...its an arrangement of electrons and kernels cause of which the metal sustains as a solid. Since Columbian forces are holding the metal together, there has to be an E.F inside the metal, or the fields of electrons and the kernels as holding each other to form the...

Can someone please tell me how charge (electrons is distributed inside a conductor with a circular cross section for example? how can charge be UNIformly distributed within it and why is it that the E field inside a conductor should always be zero? what dictates that?

If a single conductor in a transmission line dissipates 6,000kWh of energy over a 24 hour period during which time the current in the conductor was 100 amps. What is the resistance in the conductor. So could I just conver the kWh of energy to kW by dividing by 24 hours...than just use ohms...