TRANSFORMERS AND NATIONAL GRIDS
3 marks · EasyA simplified diagram of the National Grid is shown below. Complete the sentences about the use of transformers.
Describe where in the National Grid a step-up transformer is used.
Describe where in the National Grid a step-down transformer is used.
Explain why step-down transformers are needed before the electricity is supplied to homes.
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(a) At the power station, before the electricity is transmitted (to increase voltage).
(b) Near homes and businesses, before electricity is distributed locally (to decrease voltage).
(c) To reduce the voltage to a safe level suitable for use in homes and businesses.
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Marking points
B1 (a) · 1 mark · States step-up transformer is used at power station/where transmission starts.
B2 (b) · 1 mark · States step-down transformer is used near homes or local areas, before distribution.
B3 (c) · 1 mark · Explains step-down transformer reduces voltage to a safe or usable level.
Worked solution
a) Step-up transformers are used at the power station, before the electricity goes into the transmission lines. b) Step-down transformers are used near the places where electricity is needed, before it enters homes or factories. c) Step-down transformers make electricity safe to use by reducing the high transmission voltage to a lower, safer value.