Conductors Definition and 311 Threads

Homework Statement when a conductor under electrostatic equlibrium with cavity has charge inside,we say -ve charge is induced at inner surface by Gauss Law,but why do we say +ve charge induced at surface , I mean thru Gauss Law we we say Electric field has been canceled out ,why the hell...

L and K are two conductor tables, L is grounded (his potential is zero). In this situation the scales are balanced. To measure the charged object's potential, it is being connected to K with thin long conduct wire. just L and K are conductors. when the object is connected to K, L and K are...

Suppose we had an uncharged solid spherical conductor with radius R, and some spherical cavity of radius a that is located b units above R, where a+b<R. If we place a charge inside the cavity at the center, how would you quantitatively express the E-field lines outside of the conductor?

Homework Statement I am so close to this breakthrough I can taste it. I say this because I haven't taken a shower in four days. Anyways go to this link http://physics.bu.edu/~duffy/py106/Electricfield.html My questions 1) This part. OKay so a conductor is charged, all the excess...

Homework Statement http://img823.imageshack.us/img823/236/40553004.png [PLAIN][PLAIN]http://img717.imageshack.us/img717/1561/15355872.png The Attempt at a Solution I am a bit confused isn't the 6.00nC sending its own E-field? For part b) Why do they say Qinside is 0...

Homework Statement In fair weather, over flat ground, there is a downward electric field of about 150 N/C. A) assume that the Earth is a conducting sphere with charge on its surface. If the electric field just outside is 150 N/C pointing radially inwards, calculate the total charge on the...

Every book seems that it is a no-brainer that electric fields are zero in a conductor, but I do not understand this. First of all why assume it is zero just because, by contradiction, any electric field will produce acceleration in charges which cannot happen when there is electrostatic...

Hi All, I was just reading about the Thermoelectric Effect, and had a question: In this phenomenon, when there is a temperature difference on each side of a conductor with a finite resistance, a voltage develops (due to diffusion of electrons). Similarly, when a voltage is applied across a...

Hi, straight away to semiconductors. My first doubt is about why semiconductor materilas are used in making up the diodes or in any other design. why not with conductors. if you did not use doping with semiconductors then is it possible to make conduction between P-type and N-type...

Homework Statement A coaxial cable consists of a long solid inner cylindrical conductor, radius a, and a thin outer cylindrical conductor of average radius b>a. Suppose the inner conductor has a line charge density of +lambda while the outer conductor has a uniformly distributed charge of...

I have read recently about force of attraction between parallel currents and was wondering that as the force of attraction is quite small when defining an ampere... so are there any of its applications...? :shy:

Homework Statement thin wire connecting two conductors, a big sphere and a small sphere. What sphere has the most charge? Homework Equations The Attempt at a Solution The charge will want to distribute itself over the entire surface area of the two conductors. Therefore...

Homework Statement A single infinitely conductor with a diameter of 10mm and a height of 3m above ground is charged to a voltage of 20kV above earth a. Find the charge/meter on the conductor. b. Find the capacitance/meter on the conductor. Homework Equations I don't know if these...

Does the force between two current carrying conductors irrespective of their orientation act along the centre of mass? Or is it that the force acts on each point of the wire/conductor?

electric field does not exist in conductors because it gets nullified due to polarization of conductor,but in current electricity the electric field is established in a circuit(conductor) which gives drift velocity to electrons for charge flow.how can electric field exist in a circuit? please...

Are magnetic field lines around a finite current carrying straight conductor concentric circles in plane perpendicular to length of wire? I have seen texts derive an expression for it : B = μ0.i/4πd [cos Φ1-cosΦ2] where d is perpendicular distance of separation of the point...

I am a bit unfamiliar on this subject, but I know it has to do with the movement of electrons. From what I know, each atom has its own electric charge, metals are good electric conductors because the atoms have good current, so the charges can move from atom to atom easier. My question is, what...

Homework Statement Two equal sized spherical conductors are connected with a wire. Charge is placed in one conductor. What is the electric field look like? Homework Equations E=q/4pi*ep*r^2 The Attempt at a Solution I think that since these two conductors are connected by a...

I hace read in Electrodynamics from griffiths chapter 2, that, whenever acavity is inside an spherical conductor, for the outside it acts as if there was a point cherge at the center... But what if thew conductor has another shape, for example a revolution ellipsoid...?? how do you deal with...

Homework Statement in my exam, i had the following question say true or false--conductors are equipotential. what is the answer? Homework Equations The Attempt at a Solution

Homework Statement What would the electric field lines look like if two opposite charges were placed within an infinite plane conductor? Homework Equations None that I am aware of. The Attempt at a Solution I know that electric field is 0 inside of the conductor. I know...

THis isn't homework or coursework, I'm a bit old for that! Apologies if this has been posted in the incorrect place, I am just after advice from some electrical engineers. Not sure where to attack this question from so any help would be appreciated. I was talking to a friend of mine who lays...

It is known that on a wire carrying steady current there are surface charges (and hence electric field outside the wire, but let's forget about it). This surface charges play an important role to maintain a uniform electric filed along the whole wire. There are only few geometries for which one...

for the Casimir effect to be observed, why must the opposing plates be conductors?

Homework Statement Is given two parallel conductors of equal and finite length L. The distance between them is a. On these conductors flow constant currents I_1, I_2 in same dirrections. If the line which connecting their centars built angle \alpha whith dirrection of conductor find the force...

Can all conductors be inductors and could all inductors be conductors? I get confused about this because I know that inductor can be positively charges by a conductor. Can an conductor become an inductor by losing its charge from an inductor?

Homework Statement A spherical conductor of radius R1 is charged to 28 kV. When it is connected by a long, very thin conducting wire to a second conducting sphere far away, its potential drops to 12 kV. What is the radius of the second sphere as a multiple of R1? Homework Equations...

Homework Statement Describe what influence the periodic structure of a crystalline solid has on the energy distribution of the free electrons, and hence explain, in general terms, why some solids are electrical conductors and some are insulators. Homework Equations The Attempt at a...

There is something that I do not understand completely with regards to charged, isolated conductors. Gauss' law implies the following: "If an excess charge is placed on an isolated conductor, that amount of charge will move entirely to the surface of the conductor. None of the excess...

super conductors exhibit infinite current?why

Homework Statement revered members, in the attachment given by me, B1 acts perpendicular to the plane of paper and inwards and B2 acts perpendicular to the plane of paper and outwards. 1)my assumption is due to magnetic lorentz force they are acting perpendicular . but why B1 acts...

Homework Statement I have been reading electricity and magnetism by Duffin in order to understand my first year EM course. So far it has been straightforward- however, I've hit a wall when it derives the force between 2 conductors (p.117 section 5.7 if you have the book!). The book says...

can some1 clear my doubt?

Homework Statement folks, in my textbook it has mentioned 1)superconducting magnetic propulsion system plays a role in launching satellites without the help of rocket 2) superconductors are used to levitate trains above the rails and the example is bullet train i know superconductors are...

This is probably a dumb question, but I only need to know for a program I would like to write. Basically, on average (I realize there are a lot of factors involved, but a rough estimate is all I need), how much energy dissipates over a specific length of a conductor (power lines, whatever...

I’m trying to determine the how close 2 parallel infinitely long cylindrical conductors can get before they will arc together. Assume the conductors will be separated only by air, and I know that the Dielectric Strength of air is 3x10^6 V/m. So I figured that if I can come up with a formula to...

Hi all A conductor is a conductor, because it has an unfilled energy band. Likewise, insulators have filled bands, hence they do not conduct. Now, these two statements say nothing about the mobility of the electrons. How is it that an unfilled band is equivalent of mobile electrons, while a...

See picture There are two conductors with cavities, in one cavity is +q and in the other cavity is -q. If these two conductors are connected by a connecting wire, what would happen? I know the electric field must be zero over the conductors. But would it be correct to say that there is now...

Let's say you have a square plate with a voltage applied across two opposite corners, connected by the hypotenuse. Presumably, the electric current density distribution throughout the plate would be such that it would follow the path of minimal resistance, i.e. through the hypotenuse. If...

I am working to build a device that includes an air pump and heater. The pump will push air through a tube at the end of which will be a heater element. After doing some research, it seems that Nichrome is the standard heating wire for hobbies. I'm planning to have the heater in a glass-section...

Hi.. I have 2 questions ( simple once i assure you :D) in Electromagntics. 1) ""A 0.120 m long copper wire has mass of 9.02 g and is carrying a current of 5.10 A perpendicular to a uniform magnetic field. This apparatus is placed in a strong magnetic field and the wire is found to levitate...

Hello everyone, I have a (simple?) question: How do you differentiate a material to be a conductor or a semiconductor? It is just only by examining the material's electrical resistivity/conductivity whether it is low or high? Because I have heard that even some metallic conductors have high...

can anyone tell me why electrons move on the skin of an electrical conductor? I'm in gr 9, that's why this question is really simple. thanks!

Hello everyone, I have a (simple?) question: How do you differentiate a material to be a conductor or a semiconductor? It is just only by examining the material's electrical resistivity/conductivity whether it is low or high? Because I have heard that even some metallic conductors have high...

Homework Statement Two long parallel wires are separated by 4.0mm. The current in one of the wires is twice the other current. If the magnitude if the force on a 2.0m length of one of the wires is equal to 7.0μN, what is the greater of the two currents?Homework Equations...

Hello all, I am doing a research which involves hollow copper conductors. I would like to know about some kind of coolant or gas (like SF6) which can be passed through the copper tube to cool it, the temperature of the copper conductor can reach upto 100 degree C. The coolant should cool the...

Hello all, I am doing a research which involves hollow copper conductors. I would like to know about some kind of coolant or gas (like SF6) which can be passed through the copper tube to cool it, the temperature of the copper conductor can reach upto 100 degree C. The coolant should...

Hey guys, I'm researching single walled carbon nanotubes and I am trying to find out how much approx. Resistance there is in a pile of ~50nm long metallic SWCNT's piled on top of each other to form a line (think laying gunpowder for a fuse...). I'm perplexed because SWCNT's at the proper size...

Hi all I am reading about conductors and energy bands, and I undertand the math. I just need for it to be more intuitive. This is how I have understood it: We look at e.g. a semiconductor at zero temperature made of silicon . Since silicon has 4 valence electrons, these 4 electrons of one...

Can someone please help me with this problem. I don't even know where to begin after drawing the picture. Two identical conducting spheres each having a radius of 0.500 cm are connected by a light 1.80 m long conducting wire. A charge of 63.0 µC is placed on one of the conductors. Assume the...