conductor

Examples of conductor in the following topics:

• Conductors and Fields in Static Equilibrium

  • Conductors are materials in which charges can move freely.
  • For example, if a neutral conductor comes into contact with a rod containing a negative charge, some of that negative charge will transfer to the conductor at the point of contact.
  • Once the charges are redistributed, the conductor is in a state of electrostatic equilibrium.
  • Similarly, if a conductor is placed in an electric field, the charges within the conductor will move until the field is perpendicular to the surface of the conductor.
  • The conductor thus becomes polarized, with the electric field becoming stronger near the conductor but disintegrating inside it.

• Potentials and Charged Conductors

  • Electric potential within a charged conductor is equal to zero, but can be calculated as a nonzero value outside of a charged conductor.
  • All points within a charged conductor experience an electric field of 0.
  • This is because field lines from charges on the surface of the conductor oppose one another equally .
  • However, having the electric field equal to zero at all points within a conductor, the electric potential within a conductor is not necessarily  equal to zero for all points within that same conductor.
  • On the other hand, for points outside a conductor, potential is nonzero and can be defined by the very same equation, according to field and distance from the conductor.

• Conductors and Insulators

  • Based on the ability to conduct current, materials are divided into conductors and insulators.
  • All materials can be categorized as either insulators or conductors based on a physical property known as resistivity.
  • Every conductor has a limit to its ampacity, or amount of current it can carry.
  • Insulators, like conductors, have their physical limits.
  • This wire consists of a core of copper (a conductor) and a coating of polyethylene (an insulator).

• Electric Fields and Conductors

  • Electrical conductors are materials in which internal charges can move freely.
  • There is no electric field inside a charged conductor.
  • This is because all the charges in such a conductor will symmetrically oppose other charges within the conductor, causing the net result to sum to 0.
  • Curvature on the surface of a conductor allows for increased charge concentration.
  • If the surface of the conductor is flat, charge will be very evenly distributed.

• Ideal Conductors

  • An ideal conductor is one that exists only in the world of theory.
  • This is because any such field or flux that is tangential to the surface of the conductor must also exist inside the conductor, which by definition touches the tangential field or density at one point.
  • Electric flux density normal to the conductor's surface is equal to surface charge density.
  • This means that the electric field inside a perfect conductor is 0.
  • Compare conductivity and resistivity of an ideal conductor, commenting on the presence of ideal conductors in nature

• The Hall Effect

  • When current runs through a wire exposed to a magnetic field a potential is produced across the conductor that is transverse to the current.
  • The Hall effect is the phenomenon in which a voltage difference (called the Hall voltage) is produced across an electrical conductor, transverse to the conductor's electric current when a magnetic field perpendicular to the conductor's current is applied.
  • When a magnetic field is present that is not parallel to the motion of moving charges within a conductor, the charges experience the Lorentz force.
  • The Hall coefficient (RH) is a characteristic of a conductor's material, and is defined as the ratio of induced electric field (Ey) to the product of current density (jx) and applied magnetic field (B):
  • The Hall effect is a rather ubiquitous phenomenon in physics, and appears not only in conductors, but semiconductors, ionized gases, and in quantum spin among other applications.

• Dieletrics and their Breakdown

  • Dielectric breakdown is the phenomenon in which a dielectric loses its ability to insulate, and instead becomes a conductor.
  • Dielectric breakdown (illustrated in ) is the phenomenon in which a dielectric loses its ability to insulate, and instead becomes a conductor.
  • Dielectrics are commonly used either to isolate conductors from a variable external environment (e.g., as coating for electrical wires) or to isolate conductors from one another (e.g., between plates of a parallel-plate capacitor).
  • Under certain conditions, however, a material that is an insulator can become a conductor.
  • This point (the minimum voltage for the insulator to become a conductor) is known as the breakdown voltage.

• A Quantitative Interpretation of Motional EMF

  • In the case where a conductor loop is moving into magnet shown in (a), magnetic force on a moving charge in the loop is given by $evB$ (Lorentz force, e: electron charge).
  • "...... for example, the reciprocal electrodynamic action of a magnet and a conductor.
  • The observable phenomenon here depends only on the relative motion of the conductor and the magnet, whereas the customary view draws a sharp distinction between the two cases in which either the one or the other of these bodies is in motion.
  • For if the magnet is in motion and the conductor at rest, there arises in the neighbourhood of the magnet an electric field with a certain definite energy, producing a current at the places where parts of the conductor are situated.
  • But if the magnet is stationary and the conductor in motion, no electric field arises in the neighbourhood of the magnet.

• Parallel-Plate Capacitor

  • The parallel-plate capacitor is one that includes two conductor plates, each connected to wires, separated from one another by a thin space.
  • This is a capacitor that includes two conductor plates, each connected to wires, separated from one another by a thin space.
  • Between them can be a vacuum or a dielectric material, but not a conductor.

• A Microscopic View: Drift Speed

  • Good conductors have large numbers of free charges in them.
  • When charged particles are forced into this volume of a conductor, an equal number are quickly forced to leave.
  • Free electrons moving in a conductor make many collisions with other electrons and atoms.
  • The collisions normally transfer energy to the conductor, requiring a constant supply of energy to maintain a steady current.
  • Relate the drift velocity with the velocity of free charges in conductors