P4 Electric circuits

• diode

  a non-ohmic conductor that has a much higher resistance in one direction (its reverse direction) than in the other direction (its forward direction)
• electric field

  a charged object (X) creates an electric field around itself, which causes a non-contact force on any other charged object in the field
• electrons

  tiny negatively charged particles that move around the nucleus of an atom
• ion

  a charged atom or molecule
• light-depending resistor (LDR)

  a resistor whose resistance depends on the intensity of the light incident on it
• light-emitting diode (LED)


  a diode that emits light when it conducts
• line of force in an electric field

  line along which a free positive charge moves long in an electric field
• neutrons

  uncharged particles of the same mass as protons. The nucleus of an atom consists of protons and neutrons
• Ohm’s law


  the current through a resistor at constant temperature is directly proportional to the potential difference across the resistor
• parallel

  components connected in a circuit so that the potential difference is the same across each one
• potential difference

  a measure of the work done or energy transferred to the lamp by each coulomb of charge that passes through it. The unit of potential difference is the volt (V)
• protons

  positively charged particles with an equal and opposite charge to that of an electron
• resistance

  resistance (in ohms, Ω) = potential difference (in volts, V) ÷ current (in amperes, A)
• series

  components connected in a circuit in such a way that the same current passes through them
• static electricity

  electric charge stored on insulated objects
• thermistor


  a resistor whose resistance depends on the temperature of the thermistor