corona discharge

Examples of corona discharge in the following topics:

• Van de Graff Generators

  • Eventually, discharge occurs, and the belt changes polarity.
  • As the belt continues, a charging current travels via the belt, and the sphere takes on more and more negative charge until the rates at which it gains and loses charge (which occurs by leakage and corona discharge) are equal.
  • Numbers in the diagram indicate: 1) hollow metal sphere; 2) upper electrode; 3) upper roller (for example an acrylic glass); 4) side of the belt with positive charges; 5) opposite side of the belt with negative charges; 6) lower roller (metal); 7) lower electrode (ground); 8) spherical device with negative charges, used to discharge the main sphere; 9) spark produced by the difference of potentials

• Photocopy Machines and Printers

  • In the first step of xerography, a high-voltage device (either a corona wire or charge roller) charges a cylindrical drum.
  • This occurs by corona discharge, with output limited by a control grid or screen: a negative charge on the wire ionizes the space between the wire and conductor, so electrons are repelled and pushed onto the conductor.
  • The areas of the drum exposed to light then discharge to the ground; the other parts of the drum (which are not conductive, having not been exposed to light) remain negatively charged.

• Resistors and Capacitors in Series

  • We define the time constant τ for an RC circuit as $\tau = RC$. τ shows how quickly the circuit charges or discharges.
  • Discharging a capacitor through a resistor proceeds in a similar fashion, as illustrates.
  • As the voltage decreases, the current and hence the rate of discharge decreases, implying another exponential formula for V.
  • Using calculus, the voltage V on a capacitor C being discharged through a resistor R is found to be

• Static Electricity, Charge, and the Conservation of Charge

  • It can be observed in storm clouds as a result of pressure buildup; lightning (see ) is the discharge that occurs after the charge exceeds a critical concentration.

• Electric Activity in the Heart

  • The electric energy that stimulates the heart occurs in the sinoatrial node, which produces a definite potential and then discharges, sending an impulse across the atria.
  • Cells in the SA node, located in the upper right corner of the heart, will typically discharge (create action potentials) at about 60-100 beats/minute.
  • Atrial and ventricular discharge through the Purkinje trees is assigned on a standard Electrocardiogram as the P Wave and QRS complex, respectively.

• Induced Charge

  • If a charged object comes in touch with an uncharged object, or the two come sufficiently close to one another to cause a discharge that bridges the gap between them, the previously uncharged object will become charged.

• Charge Separation

  • It can have an extreme effect if it reaches a critical level, whereat it becomes discharged.

• Thermal Pollution

  • Some fish species will avoid stream segments or coastal areas adjacent to a thermal discharge.

• The Bohr Model of the Atom

  • However, late 19th century experiments with electric discharges have shown that atoms will only emit light (that is, electromagnetic radiation) at certain discrete frequencies.