QVIRt

• Current

  The rate of flow of charge in a circuit.

  Current= charge/time
• Ammeter

  A device that measures the current in the loop of the circuit that it is connected in series with. An ideal ammeter is modelled to have zero resistance.
• Charge carriers

  Charged particles that move through a substance when a pd is applied across it.
• Potential difference

  the work done per unit charge in moving a charge between two points in an electrical field.

  P.D= energy/charge
• Voltmeter

  A device used to measure the potential difference across components. An ideal voltmeter is modelled to have infinite resistance.
• Resistance

  A measure of how difficult it is for current to flow through a material.

  P.D= current x resistance
• Ohm’s law

  The current and potential difference through an ohmic conductor held under constant physical conditions are directly proportional, with the constant of proportionality being resistance.
• Resistivity

  A quantity that is proportional to an object’s resistance and cross sectional area, and inversely proportional to an objects length

  How difficult it is for current to flow,

  account for structure of metal and temperature each metal has a different value of resistivity for every temperature

  Resistive= (resistance x cross sectional area)/length
• Superconductor

  A material which has zero resistivity when the temperature is decreased to, or below, the materials critical temperature. superconductors can be used to produce strong magnetic fields and reduce energy loss when transmitting power
• Ohmic conductor

  A conductor for which the current flow is directly proportional to the potential difference across it, when under constant physical conditions.
• Light dependent resistor

  A light sensitive semiconductor whose resistance increases when light intensity decreases.
• Thermistor

  A temperature sensitive semiconductor whose resistance increases when temperature decreases.