P6: Electric circuits

Electronic circuit symbols



Circuits

  • A series circuit is a circuit which only has one path the current can flow
  • A parallel circuit is a circuit which has more than one path the current can flow
  • The cells in a series have the same combined electrmotive forces as the sum of the individual ones (cells with electromotive forces of 1V, 2V, and 3V each will have a combined electromotive force of 6V)
  • The resistors in a series have the same combined resistance as the sum of the individual combined resistance
  • In parallel circuits, the current splits up into different branches (with branch having less current than the source)
  • This also means that the current from the source is also equal to the sum of the current in the branches of the parallel circuit
  • Parallel circuits have their advantages. They are able to be individual control lights through individaul switches. Also, in parallel circuits, in the case that one part stops functioning, the rest of the parts can continue to function


Parallel (left) and series (right) circuits



The formula to calculate power is equal to current x voltage. The formula to calculate energy is curent x voltage x time



Dangers of electricity

  • There are different electrical hazars that make electricity dangerous. This includes...
    • Damaged insulation: Damaged insulation causes wire to be exposed. Contact with this exposed part of wire could cause an electric shock
    • Cable overheating: When a lot of current passes through a small wire, it overheats and could burn and melt the insulators to expose the wire parts
    • Damp conditions: When working wires are in contact with moisture, the moisture conducts electricity and could cause electrocution


Fuses

  • Fuses are safety devices in circuits breaks the circuit and cuts off electricity in the case that too much current flows within the circuit
  • This is to prevent the wire from exposing dangers, such as the heating or melting of wires
  • Fuses come in different sizes. In order to select the correct size, we need to know the amount of current the appliance needs. The fuse to use should be the one that is the size above the current needed


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