insulator

Examples of insulator in the following topics:

• 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.
  • While there is no perfect insulator with infinite resistivity, materials like glass, paper and Teflon have very high resistivity and can effectively serve as insulators in most instances.
  • Just as conductors are used to carry electrical current through wires, insulators are commonly used as coating for the wires.
  • This wire consists of a core of copper (a conductor) and a coating of polyethylene (an insulator).

• Dieletrics and their Breakdown

  • In all applications, they are selected for their ability to act as insulators.
  • By definition, an insulator is unable to conduct electricity.
  • Under certain conditions, however, a material that is an insulator can become a conductor.
  • Eventually, exposing any insulator to increasing voltage will result in the insulator becoming conductive.
  • This point (the minimum voltage for the insulator to become a conductor) is known as the breakdown voltage.

• Capacitors with Dielectrics

  • This interruption can come in the form of a vacuum (the absence of any matter) or a dielectric (an insulator).
  • Any insulator can be used as a dielectric, but the materials most commonly used are selected for their ability to resist ionization.
  • Eventually every material has a "dielectric breakdown point," at which the potential difference becomes too high for it to insulate, and it ionizes and permits the passage of current.

• Safety Precautions in the Household

  • This wire is therefore safe to touch even if its insulation is missing.
  • Under ordinary circumstances, insulation on the live/hot and neutral wires prevents the case from being situated directly within the circuit, so that the earth/ground wire may seem like double protection.
  • The simplest problem is worn insulation on the live/hot wire that allows it to contact the case.
  • These appliances, including power tools with impact resistant plastic cases, have nonconducting cases and are called 'doubly insulated. ' Modern two-prong plugs can be inserted into the asymmetric standard outlet in only one way, ensuring the proper connection of live/hot and neutral wires.
  • Wire insulation colors vary by region.

• Parallel-Plate Capacitor

  • The dielectric between the conductors is meant to act as an insulator, preventing charge from bridging the gap between the two plates.
  • In practice, dielectrics do not act as perfect insulators, and permit a small amount of leakage current to pass through them.

• Back EMF, Eddy Currents, and Magnetic Damping

  • There is no discernible effect on a bob made of an insulator.
  • When an insulating material is used, the eddy current is extremely small, and so magnetic damping on insulators is negligible.
  • If eddy currents are to be avoided in conductors, then they can be slotted or constructed of thin layers of conducting material separated by insulating sheets.

• Humans and Electric Hazards

  • Usually the best way to help the victim is to give the fist a hard blow with an insulator or to throw an insulator at the fist.
  • (a) Worn insulation on the wires of a toaster allows them to come into contact with a low resistance r.

• Convection

  • Although air can transfer heat rapidly by convection, it is a poor conductor and thus a good insulator.
  • The amount of available space for airflow determines whether air acts as an insulator or conductor.
  • The addition of wall insulation prevents airflow, so heat loss (or gain) is decreased.

• Constant Pressure and Volume

  • We may say that the system is dynamically insulated, by a rigid boundary, from the environment.

• Parallel-Plate Capacitor

  • The maximum energy (U) a capacitor can store can be calculated as a function of Ud, the dielectric strength per distance, as well as capacitor's voltage (V) at its breakdown limit (the maximum voltage before the dielectric ionizes and no longer operates as an insulator):