• A?transformer?is an electrical device that can be used to increase or decrease the?potential difference?of an?alternating current
  • This is achieved using the?generator effect

   

Structure of a Transformer

• A basic transformer consists of:
  • A?primary coil
  • A?secondary coil
  • An?iron core

   

• Iron is used because it is easily?magnetised

Structure of a transformer

How a Transformer Works

• An?alternating current?is supplied to the?primary coil
• The?current?is continually?changing direction
  • This means it will produce a?changing magnetic field?around the primary coil

   

• The iron core is?easily magnetised, so the changing magnetic field passes through it
• As a result, there is now a?changing magnetic field?inside the?secondary coil
  • This changing field?cuts?through the secondary coil and?induces a potential difference

   

• As the magnetic field is continually changing the potential difference induced will be?alternating
  • The alternating potential difference will have the?same frequency?as the alternating current supplied to the primary coil

   

• If the secondary coil is part of a?complete circuit?it will cause an?alternating current?to flow

• A transformer can change the?size?of an alternating voltage
• They also have a number of other roles, such as:
  • To increase the potential difference of electricity before it is transmitted across the national grid
  • To lower the high voltage electricity used in power lines to the lower voltages used in houses
  • Used in adapters to lower mains voltage to the lower voltages used by many electronic devices

   

• A?step-up?transformer?increases the potential difference?of a power source.
  • A step-up transformer has?more?turns on the secondary coil than on the primary coil

   

• A?step-down?transformer?decreases the potential difference?of a power source.
  • A step-down transformer has?fewer?turns on the secondary coil than on the primary coil

   

Transformers in Electricity Transmission

• When electricity is transmitted over large distances, the?current?in the wires?heats?them, resulting in?energy loss
• The electrical energy is transferred at?high voltages?from power stations
• It is then transferred at?lower voltages?in each locality for domestic uses
• The voltage must be stepped up by a?step-up?transformer
  • These are placed?after the power station

   

• For the domestic use of electricity, the voltage must be much lower
• This is done by stepping down by the voltage using a?step-down?transformer
  • These are placed?before buildings

   

Electricity is transmitted at high voltage, reducing the current and hence power loss in the cables using transformers

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