What is Conductors: Definition and 311 Discussions

Black conductors are musicians of African, Caribbean, African-American ancestry and other members of the African diaspora who are musical ensemble leaders who direct classical music performances, such as an orchestral or choral concerts, or jazz ensemble big band concerts by way of visible gestures with the hands, arms, face and head. Conductors of African descent are rare, as the vast majority are male and Caucasian.

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  1. Ignitia

    How Does Gauss' Law Apply to a Spherical Conducting Shell with a Central Charge?

    Homework Statement A point charge q=−5.0×10−12 C is placed at the center of a spherical conducting shell of inner radius 3.5cm and outer radius 4.0 cm. The electric field just above the surface of the conductor is directed radially outward and has magnitude 8.0 N/C. (a) What is the charge...
  2. J

    Question about concentric conductors

    Homework Statement Three insulated concentric spherical conductors, whose radii in ascending order of magnitude are ##a, b, c##, have charged ##e_1, e_2, e_3## respectively, find their potentials and show that if the inner most sphere is grounded, the potential of the outermost is diminished...
  3. T

    Confusion about induction in conductors

    Homework Statement Homework EquationsThe Attempt at a Solution a) charge induced is ##\frac{-q_i}{4 \pi r_i^2} = \sigma_i## ##\frac{q_a + q_b}{4 \pi R^2} = \sigma_R## b) field outside is ##\frac{k (q_a + q_b)}{r^2}## c)i naively applied gauss law to get field within each cavity as...
  4. Aastik Tripathi

    Modification in Coulomb's Law and its implications

    If the coulomb's law instead of following an inverse square relationship, follows an inverse cube relationship, How would it affect an isolated charged conducting sphere? How would it's field vary within the volume and how would the volumetric charge density be affected? Please give in some...
  5. F

    Ionized Gas Cables: Can You Buy Them?

    Hi! Does it exist cables using ionized gas / plasma as the conductor available to buy? Thanks in advance!
  6. G

    Coaxial cable conductors with dielectric: polarization of charge

    Homework Statement Consider a coaxial cable which consists of an inner cylindrical conductor of radius R1, and a shell cylindrical conductor of radii R2 and R3. The 2 conductors are separated with a dielectric material of permittivity ε. Consider the length of the cable, ℓ, much larger than R3...
  7. S

    Can liquid conductors be used to improve the efficiency of electric motors?

    Hello! I found this interestingly amazing forum accidentally while searching for info on conductive liquids. Please let me explain... I have built an electric motorcycle conversion (EMC) and am in the planning stages of upgrading the drive system from a PMDC...
  8. NFuller

    Charge sharing between two conductors

    This is a question born out of a homework thread that lead to a discussion between @haruspex, @rude man, and myself. Link here https://www.physicsforums.com/threads/what-is-the-charge-of-each-conductor-afterwards.923909/ . I feel this question deserves its own thread and hopefully we can get...
  9. L

    B Why is resistivity important in solving this problem?

    In free space there are two masses: - Metallic sphere of mass M, radius R and total charge equal to 0. It has also a resistivityρ. - Metallic sphere of mass m, radius r and charge q. The distance between the masses is D. We can assume r <<R<<D and m<<M. The masses start accelerating until they...
  10. M

    Charge, conductors, voltage and EPE questions?

    This is 'optional homework' that the teachers don't see and we write down just to practice. So I want someone to review it and tell me if I truly understand these concepts :) thanks in advance 1.What is the smallest charge (quantum of charge) that any paricle an exert? A: An electron/proton of...
  11. T

    How Does Charging a Conducting Shell Affect Potential Difference?

    Homework Statement A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow spherical shell.Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be V.If the shell is now given a...
  12. T

    What Is the Potential of an Uncharged Conductor Near a Charged Conductor?

    Homework Statement Consider a finite,uncharged,insulated conductor placed near a finite positively charged conductor.The uncharged body must have a potential A)less than the charged conductor and more than at infinity B)more than the charged conductor and less than at infinity C)more than the...
  13. C

    Surface density on isolated conductors in space

    Homework Statement There are n isolated condutoctors in space: Sum of charge of all conductors is positive. Show that surface density is postivie everywhere on at least one of conductors Homework Equations Using induction The Attempt at a Solution -It's clear that if we have one conductor...
  14. shihab-kol

    Why do conductors have a sea of electrons while insulators don't?

    Why is a sea of electrons present in a conductor? I read some where that they absorb a energy at normal temperatures and use it to get free electrons , but then why do they absorb energy while insulators don't??
  15. mohau tshekoeng

    How to manipulate Ohmic conductors

    How to change an ohmic conductor to a non-omic conductor over a short period of time
  16. L

    I Forces between two straight conductors

    Hi, I am having trouble figuring out how the forces work between two straight conductors with currents going through them. I know that when the currents go the same way, the forces are attractive, and when the currents go opposite ways, the forces are repelling. I know one has to use the right...
  17. R

    Excess charge on insulators and conductors

    From what I've learned, excess charge on an insulator stays where it is but excess charge on a conductor spreads uniformly throughout its surface. Why does this happen? Can this be explained in terms of electrostatic potential?
  18. franktherabbit

    Determining the capacitance of the two conductors

    Homework Statement For a given system, a conducting cylinder with radius ##r=a## with a linear charge density ##Q'## and a conducting surface at a distance ##z=h## from the cylinder, calculate the linear capacitance of the cylinder.Take that ##h>>a## ##C'=\frac{Q'}{U}## Homework Equations 3...
  19. W

    How Do Metals Affect Electric Fields and EM Waves?

    hi, i want to ask explanation that if in front of electric fields lines comes a metal plate, than as far i know electric field does not pass through it, but how would i expalin as electric field can exert force on free electrons.
  20. N

    The magnetic field within cylindrical hollow conductor

    Hi, While studying the coaxial cable, i noticed that the magnetic field of the inner conductor can pass through the hollow conductor (can be calculated in the region 3). However, the boundary condition of the magnetic field at the surface (between dielectric and perfect conductor) of a perfect...
  21. math4everyone

    What is the electric field at a point along the z-axis above a charged dome?

    Homework Statement Homework Equations The z component of the field: $$E_z = \frac{-Qh}{2\pi\varepsilon_0 (r^2+h^2)^{\frac{3}{2}}}$$ The Attempt at a Solution I tried to choose a cylinder for my Gaussian surface such that the radius of it matches with the distance d I am trying to find and...
  22. N

    Why are conductors not used to store electricity?

    I read somewhere that conductors don't really store charge? How can this be correct? When a conductor is charged by conduction, the electrons spread throughout the surface of the conductor. Doesn't this mean that the capacitor is storing this electricity? What prevents conductors from being...
  23. J

    I Forces Between 2 large conductors

    If I have two large cunducting bars (not the same size) that are separated by a distance D but connected with another conductor in between creating a "U" shape and apply a large current through it, how can I calculate the magnetic forces between the two large ends of the "U" shape? I have...
  24. W

    Induction: Questions reg. Coils vs Parallel Conductors

    Needing a bit of help here. I am trying to transfer an AC signal to a straight conductor via induction. I am trying to quantify the difference in amount of transferred signal (amps) when the source of the signal is a small coil versus a parallel running straight conductor. I am thinking its...
  25. B

    Introducing Local Charge to Conductors?

    Homework Statement Is it possible to introduce local charge on a conductor? Homework Equations - The Attempt at a Solution I know that electrons can move freely from atom to atom in the conductor, so if you introduce excess electrons to the conductor, they'll spread out and there won't be a...
  26. T

    How does charge distribute on connected conductors

    This is a question that is vaguely related to coursework but is more for curiosity. Lets say there are two spheres joined by a thin wire in the presence of an electric field: Assume the conductors initially have no charge. Now I am pretty sure without the wire, the charge distribution would...
  27. S

    B Question about understanding conductors for EM course

    So in conductors, the electrons will distribute themselves to the surface via repulsion forces. But why do we say that the electric field inside is zero? If I put a positive charge inside, clearly it will move in some direction from the electric field of generated from the electrons. Also, are...
  28. P

    Three concentric spherical conductors -- Find the potential

    Homework Statement I am not sure whether to put this in the introductory level or advanced. It seems to be relatively introductory in an electromagnetism course. A spherical conductor of radius ##a## carries a charge ##q##. It is situated inside a concentric spherical conducting shell of...
  29. P

    What is the charge on the outer surface of the middle conductor?

    Homework Statement Three concentric hollow spherical conductors are charged as follows: the inner conductor carries charge Q, the middle conductor carries charge -2Q, and the outer conductor carries charge -Q. What is the charge on the outer surface of the middle conductor? Homework Equations...
  30. person_random_normal

    Charge on Conductors - David J Griffiths

    - David J Griffiths But how s it valid for some conductor like →
  31. A

    Electron movement in conductors

    This is not a normal problem help topic. The difficulty I've encountered is in understanding an alternative solution. 1. Homework Statement In a real conductor, electrons (with mass m), conducted by external electric fields, constantly collide with defects and impurities within the conductor...
  32. U

    I Conductors and Insulators question

    So a charged object can induce a charge on both conductors and insulators. For the conductor, (assuming a negative object is brought near it), all the negative charge would flow to one side creating a strong attractive force. For an insulator, what exactly happens? I understand there will be a...
  33. N

    Would two conductors of same charge touch or not touch?

    Homework Statement Homework Equations I need help with part c for part (a) I got 18 m/s and for part (b) I said the velocity would be zero after a long time has passed, assuming that there is gravity. The Attempt at a Solution For part (c) I would assume that they would not touch because...
  34. S

    Can conductors be accelerated enough to emit electrons?

    Can it be done with technology available today? How would you begin to formulate the forces needed? I am assuming the work function is needed.
  35. P

    Electric Field & Potential from Two Conductors

    Homework Statement Two isolated, concentric, conducting spherical shells have radii R1=0.500 m and R2=1.00 m, uniform charges q1=2.00 mC and q2=1.00 mC, and negligible thicknesses. What is the magnitude of the electric field E at radial distance (a) r=4.00 m, (b) r=0.700 m, and (c) r=0.200 m...
  36. E

    Grounding parallel plate conductors

    Homework Statement So, I always make mistakes on problems such as this (the grounding part), so I'm hoping someone could really explain to me how the process works instead of just answering this particular problem. There are n large parallel plate conductors carrying charges Q1, Q2,... Qn...
  37. gracy

    Problem related to two conductors in contact

    Homework Statement An isolated conducting spherical shell carries a negative charge. What will happen if a positively charged metal object is placed in contact with the shell interior? Discuss the three cases in which the positive charge is a) less than , b) equal to, and c) greater than the...
  38. F

    Potential difference on circuit conductors....

    Hello Forum, Consider a simple DC circuit composed of a battery (say 2V), conducting wires and a single resistor R=2 Ohm The potential difference across the resistor will be exactly 2V only if the wires were superconductors (zero resistance). But wires do have some small finite resistance so...
  39. K

    Dumb question about conductors in electric field

    I've read multiple times that electric field inside of the conductor is always equal to zero because the inner field produced by electrons that moved to one side and left protons on another balance the outer field. I've also read about Faraday cage. But I have a few questions about this: 1) So...
  40. G

    Capacitance per unit length - two cylindrical conductors

    Homework Statement Two cylindrical conductors, of distance between them d and radius a (a<<d), have dielectric layer of relative permitivitty εr and thickness a. Calculate capacitance per unit length of this system. Homework Equations Capacitance per unit length, C'=Q'/U Gauss law, cylindrical...
  41. T

    Two touching neutral conductors in electric field separate?

    Homework Statement Given a situation like this: Where the two blocks are perfectly conducting materials and are touching, will they separate? If they do separate, will they have the net charge values you calculate in the initial setup using Gauss's Law? There are no numbers, it's just...
  42. neduet

    132 kv transmission line towers and conductors

    Dear friends 1.What is wind span ,wight span and normal span, and what is the difference. 2. Factory acceptance test. FAT. For towers what is that meaning and what is necessary test to be require to do or check. Thanks
  43. neduet

    Selecting conductors for transmission line 132kv 100MW 95km

    Hello dears i want to know which is best for 132kv transmission line. advantages and disadvantages as in prectical use. but also consider economical factor wisely . what you chose if you are in my place... ACSR Conventional AAAC ( All Aluminium Alloy Conductors ) ACCC Aluminum Conductor...
  44. E

    Why is the expression for sheet resistance given without demonstration?

    Hello! I have in my notes an expression for the sheet resistance of a uniform conductor with length L, width W = L and thickness t. It is R_{\square} = \displaystyle \frac{\sqrt{\displaystyle \frac{\pi f \mu}{\sigma}}}{1 - e^{-t/\delta}} = \displaystyle \frac{1}{\sigma \delta} \frac{1}{1 -...
  45. G

    System of hollow cylindrical conductors

    Homework Statement Find potential and charge per unit length of every cylindrical hollow shell if the outer shell is grounded. The length is considered to be infinite. Homework Equations V=∫Edl The Attempt at a Solution I am not sure how to derive potentials for first two conductors...
  46. Z

    How Does Grounding Affect Charge Distribution on a Conductor?

    So I am extremely confused at the moment. We had a hollow ring in physics lab today. There was a positive charge (30V) inside the sphere that was no centered and then the ground was attached to the ring itself (0 V). So, I understand that the negative charges unevenly distribute to cancel the...
  47. G

    Electrostatics:Longitudinal charge density of conductors

    Homework Statement Three very long (theoretically infinite long) hollow cylindrical conductors, with radius a,b,c (c>b>a) are in vacuum. Inner and central conductor are charged, and outer conductor is grounded. Potentials of inner and central conductors with reference point relative to outer...
  48. carllacan

    Difference between conductors and empty space

    Inside a conductor, as opposed to inside an insulator, charges are free to move around and reposition themselves, which causes that, if we wait a long enough time, the electric field inside them will be zero. But in an empty space there's nothing (by definition) that can stop charges from...
  49. C

    A.C. resistance of non-cylindrical conductors

    Hi, Can someone please explain how to calculate the A.C. resistance of non-cylindrical conductors? All the references I can find online assume round wires and I'm not sure the same equations would apply for other geometries? Thanks, Chris
  50. U

    Charge inside and outside conducting shell

    A thin metallic spherical shell contains a charge Q over it. point charge +q is placed in side the shell at point T separated from the centre by a distance a. Another point charge q1 is placed outside the shell at a distance b from the centre find the electric field at the centre due to the...
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