Use of Transformers
- Transformers have a number of roles:
- They are used to increase the potential difference of electricity before it is transmitted across the national grid
- They are used to lower the high voltage electricity used in power lines to the lower voltages used in houses
- They are used in adapters to lower mains voltage to the lower voltages used by many electronic devices
- The type of current produced in power stations is alternating current (AC) which is transferred through to homes via the National Grid
- Transformers are used to increase and decreases the potential difference of the AC electricity before and after transmission across the National Grid
- Step-up transformers are used to increase the potential difference from the power station to the transmission cables
- Step-down transformers are used to decrease the potential difference, to a much lower value, from transmission cables for domestic use (houses, offices, shops)
Worked example
The diagram shows part of the National Grid.
Explain how the step-up transformer increases the efficiency of the National Grid.
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- The lower the current, the less heating there will be in the wire because there will be less resistance in the wires
- From the diagram, the step-up transformer increases the voltage and decreases the current in the power cables
- By decreasing the current of the transmitted electricity, the energy lost through the power cables is reduced
- Therefore, there is more energy to be supplied to the homes which increases the efficiency of the National Grid
Examiner Tip
Make sure you remember step up and step down in the correct order. Step up increases the voltage and step down decreases the voltage.
