circuit components

• Switch


  A device for making and breaking the connection in an electric circuit.

  
• Cell


  A device used to generate current, in which chemical energy is converted into electricity and used as a source of power.

  
• Battery


  A container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power.

  
• Diode


  A device that permits current to flow through it in only one direction.

  
• Resistor


  A device used to introduce some amount of resistance into a circuit.

  
• Variable Resistor


  A resistor whose resistance can be changed.

  
• LED


  Light-emitting diode. An electronic device that conducts current in one direction only and illuminates when it is conducting.

  
• Lamp


  A light source produced by resistance.

  
• Fuse


  A safety device consisting of a strip of wire that melts and breaks an electric circuit if the current exceeds a safe level.

  
• Voltmeter


  A device used to measure voltage (potential difference) around a component. Always placed in parallel with the component.

  
• Ammeter


  A device used to measure current in a circuit. Always placed in series.

  
• Thermistor


  A resistor that changes its resistance with a change of temperature.

  
• LDR


  Light dependent resistor, a resistor whose value of resistance can change as the intensity of the light falling on it changes.