Definition of the National Grid: Network of pylons and cables that covers the whole of Britain supplying electricty to homes everywhere.
1) To supply all the homes along the National Grid, it either needs a high voltage or a high current. High current means you lose a lot of heat energy through the cables. Its easier to boost the voltage up highly and keep the current low.
Definition of a step-up transformer: Increases the voltage for efficient transmission through the cables and pylons.
Definiton of step-down transformer: Decreases the volatge before being supplied to the consumer for…