Key terms

• Alternating Potential Difference

  A continually oscillating current flow, which results in the potential difference across 2 points continually oscillating between a positive and a negative value.
• Amps (A)


  The unit of current
• Attraction

  A force pulling 2 opposite charges together, when they are near each other.
• Coulomb (C)


  The unit of charge
• Diode

  A component that only allows current to flow in the forward direction because it has a tonne of resistance in the opposite direction.
• Direct Potential Difference

  A one direction current flow.
• Earth Wire

  The green and yellow striped wire that prevents an appliance from becoming live.
• Electrical Field Lines

  Lines representing an electric field that point in the direction in which a positive charge would experience an electrical force.
• Electrical Current

  The rate of flow of electrical charge. It's value is the same at every point in a single closed loop.
• Electric field

  A region in which a charge will experience a non-contact, electrical force. All charged objects have an electrical field around them, and this field is stronger the closer you are to the charge.
• Electrical work

  When charge flows in a circuit, electrical work is said to be done.
• Filament lamp

  A light emitting component consisting of an enclosed metal filament. It's resistance increases as the filament's temperature increases.
• Insulation

  The coating around power cables that prevent electrocution and is colour coded to allow for easy identification.
• Light Dependent Resistor (LDR)

  A light dependent component who's resistance increases as it's temperature decreases.
• Live Wire

  The brown coloured wire that carries alternating current from the supply in a mains power circuit.
• Mains Electricity

  An a.c. circuit, which in the U.K. has a frequency of 50Hz and a value of 230V
• Neutral Wire

  The blue coloured wire that completes the circuit in a mains power supply.
• Non-contact force


  A force experienced between 2 separated objects.
• Ohmic conductor

  A conductor whose current flow is directly proportional to the potential difference across it, when held at a constant temperature.
• Ohms

  The unit of resistance
• Parallel

  Components connected in a parallel have the same potential difference across each component. The total current is equal to the sum of all currents flowing through every component.
• Potential Difference

  The product of the current and resistance flowing through a circuit.
• Repulsion

  Caused when two like charges are brought near each other.
• Resistance

  A measure of the opposition to current flow.
• Resistors in Parallel

  The total resistance of 2 or more Parallel components is always lower than the lowest quanity of resistance.
• Resistors in series

  The total resistance is equal to the sum of the individual resistances of each component.
• Series


  Components in series have the same current passing through each component but share the total potential difference of the circuit's supply.
• Static charge

  The charge caused by an imbalance of positive and negative charges in, or on, an object's surface. It is often caused by electrons being rubbed from one surface onto another.
• Step down transformers

  Devices found between the transmission cable and the consumer that lowers the potential difference of the power so it's at safe, usable levels.
• Step up transformers

  Devices that increase the potential difference generated by a power station, so the electrical power transmitted along the transmission cables is at a higher potential.
• The National Grid

  The network of power stations, transformers and cables that connect consumers to power stations.
• Thermistor

  A temperature dependent component, whose resistance increases as it's temperature decreases.
• Volt (V)


  The unit of potential difference