# Understand the National Grid

In this worksheet, students will learn the components that make up the National Grid and revise the use of AC and DC electricity.

Key stage:  KS 4

Year:  GCSE

GCSE Boards:   AQA, AQA Trilogy, AQA Synergy, OCR 21st Century, OCR Gateway, Pearson Edexcel, Eduqas,

Popular topics:   Physics worksheets

Difficulty level:

#### Worksheet Overview

There are some interesting rivalries in science. Newton and Hooke had a rivalry so strong that when Hooke died, Newton had all of Hooke’s portraits burnt. Einstein had a rivalry with himself – basically discovering a branch of science called quantum mechanics and then spending his life trying to disprove it. But there has been no greater rivalry than that of Nicola Tesla (the one the cars are named after) and Thomas Edison (the person who invented the light bulb).

Tesla was born in Croatia and moved to America when he was young to try and earn some money. He was a painfully shy person, choosing to spend time in his room, not going out and only talking to people when it was necessary. Edison, however, was called the wizard of Maranello – an outgoing and brutal businessman who spent a lot of time showing off his inventions (including the light bulb) in order to make more money.

Edison wanted to make electricity something that every American could enjoy – for a price that would make him the richest person in the world. There was one problem with the plan – using his DC electricity, he couldn’t transport his electricity very far before it all leaked out of the wires.

Frustrated with this, Edison issued a challenge to the young Tesla, who he had employed based on his reputation. He said ‘If you find a way of transporting electricity more effectively, I’ll pay you \$50,000’, which is about \$10 million now. Tesla, obviously impressed with this amount and the challenge, worked day and night for months and came up with a solution – he called it AC. Edison took this idea and when Tesla asked to be paid, Edison laughed at him and said ‘You don’t understand American humour, I was never going to pay you’.

Tesla quit working for Edison and moved to work with Westinghouse where it was his aim to make electricity free for everyone. Edison didn’t like this and started a smear campaign, electrocuting elephants and people using Tesla’s AC, as a way of showing how dangerous it was (but DC was actually more dangerous). But what is the difference between AC and DC, I hear you cry? Let's take a look at them.

Things to remember:

1   In AC (or alternating current), the electrons move from side to side. This is done at a speed of about 50 times every second (50 Hz) in the UK. AC is safer and wastes less energy than DC.

2   In DC (or direct current), all of the electrons flow around the circuit as you would expect them to. This is the type of electricity you get in batteries, and it is really useful for things like phones and computers. They almost always need a DC supply and so most of them have to convert the AC they get from the plug into DC.

The benefits of AC won out in the end and Edison started using it to distribute his electricity as well. This made Edison the richest man in the world at the time and Tesla died with hardly any money.

What does this have to do with the National Grid? Well, we still use Tesla's AC in our National Grid today – let’s take a look at it.

The important parts to remember in this image are:

1  Those dark grey boxes are called transformers, and they change the voltage up and down. A high voltage will make it very efficient to send the electricity a long way, but it needs to be moved back down so it can be used in your house.

2   The voltage in the 'high tension' wires is about 400,000 V and in your home, it is about 230 V.

3  This ONLY works with AC, not DC. This is why Tesla's idea was better!

Now for some questions.

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