Physics p1 - THE NATIONAL GRID.

• National grid - an electric power network that connects power stations.

• Step up transformer - the voltage is incresed.

• Step down transformer - the voltage is decreased.

• Pylons - the power lines that carry the power lines.

• Power station -  where all the electrical energy is generated.

The national grid gets the elecrical energy from the power stations and delivers it to wherever it is needed.

For a large amount of power, a high voltage or current is required. Although, to make the whole process more efficient, and so heat energy isn't lost in the cables, we use step up transformers, these boost the voltage up to 400,000V, but the current stays very low.

But of course, homes cannot use so much voltage, it would be dangerous! So we use step down transformers to make the voltage to safe levels.

• The purpose of a step up transformer is that, if you need to supply a large voltage to an object that requires a large voltage, say a factory or big business, we can supply this safely and they can get the right amount of voltage needed.

• The purpose of a step down transformer is to safely deliver the correct amount of voltage to houses. If you have just used a step up transformer to deliver a large amount of voltage to a facotry, the voltage has to be changed before it gets to someone's house, as this is dangerous!

• The average voltage supplied to a house is roughly 140V.

• What voltage does a step up transformer boost the voltage to?

• What is the name of the power network that connects the power stations?

• Explain why step up and step down transformers are used.

• What decreases the voltage?

• When you have a high current, you lose a lot of ____ energy in the cables.                                                     

                                                                (Next page for answers, don't cheat!)

• 400,000V

• The national grid.

• Step up transformers increase the voltage up and step down transformers decrease the voltage.

• Step down transformer.

• Heat