6.18 explain the use of step-up and step-down transformers in the large- scale generation and transmission of electrical energy

Transformers are used in the National Grid. This is because the wires are long there is more resistance, so a high current will cause a lot of heat which is dangerous and looses a lot of energy (it is not energy efficient). When electricity leaves a power plant/generator, a step up transformer is used, this increased the voltage but decreases the current. When electricity reaches nearby the areas it is to be used, for example factories and edge of towns, it is stepped down. Once the wires reach a home or business it is stepped down once more (to 230v) to make it useful in appliances that we use.