The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Understand the National Grid

Worksheet Overview

QUESTION 1 of 10

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 National Grid

 

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.

In the modern National Grid system, do we use AC or DC?

AC

DC

Do batteries use AC or DC power? 

AC

DC

From the list below, choose the correct value for mains voltage in the UK, as well as the frequency of the power supply.

What is the function of a transformer? 

Change the voltage

Change the current

A robot in disguise

Change the resistance

Match the parts of the National Grid listed below with the order in which they are placed in the system.

Column A

Column B

1
Step-up transformer
2
Generator
3
Step-down transformer
4
High tension wires
5
Home

Power is lost in the transfer of electricity along wires.

 

Complete the sentence with one word:  "The energy is lost as..."

Describe the function of a step-down transformer. 

 

[2]

Describe the function of the National Grid. 

 

[1]

Compare AC and DC in terms of movement of electrons. 

 

[2]

Describe what happens to the electricity when it goes through a step-up transformer. 

 

[2]

  • Question 1

In the modern National Grid system, do we use AC or DC?

CORRECT ANSWER
AC
EDDIE SAYS
How did you do with this one? If you're not sure what AC and DC mean, it would be a good plan to go back to the Introduction and have another read before continuing with the questions. AC, or alternating current, is used in the modern National Grid - only AC is able to work with the transformers that are needed to transmit electricity effectively over a long distance, without losing a huge amount.
  • Question 2

Do batteries use AC or DC power? 

CORRECT ANSWER
DC
EDDIE SAYS
Batteries are a store of DC power - they provide a constant flow of electrons to the circuit, instead of moving them backwards and forwards. This is much better for electrical circuits but means that the power cannot be transmitted over long distances. That's why you will find many things such as toys and remote controls powered by batteries rather than by mains electricity.
  • Question 3

From the list below, choose the correct value for mains voltage in the UK, as well as the frequency of the power supply.

CORRECT ANSWER
EDDIE SAYS
This is a case of just trying to remember the facts, but if we are being totally honest, there are much more important things for you to remember! The most this will ever get you is two marks, but something like remembering the circuit symbols could get you a lot more marks. All we're saying is be intelligent about what you put your time and effort into.
  • Question 4

What is the function of a transformer? 

CORRECT ANSWER
Change the voltage
Change the current
EDDIE SAYS
A transformer needs to change both the voltage and the current of the electricity that is passing though it. It needs a low current, so it wastes as little energy as possible when it is going through the wires. It achieves this by having a really high voltage, so most of the energy can stay in the wires.
  • Question 5

Match the parts of the National Grid listed below with the order in which they are placed in the system.

CORRECT ANSWER

Column A

Column B

1
Generator
2
Step-up transformer
3
High tension wires
4
Step-down transformer
5
Home
EDDIE SAYS
How did you do with this one? Take it one step at a time through the whole process of generating electricity. 1 You need to make (generate) the electricity, so we need to start off with a generator. 2 You need the voltage to be as high as possible when transmitting the electricity - it needs to be stepped up. This means you need a step-up transformer next. 3 You need to move the electricity through cables - these are held at a high voltage, so they are high tension cables. 4 You need the voltage to be brought back down to 230 V before it goes into the house, so you will need a step-down transformer to put it back to the normal 230 V. 5 Your house needs the electricity - so you need to put your house in there at the end.
  • Question 6

Power is lost in the transfer of electricity along wires.

 

Complete the sentence with one word:  "The energy is lost as..."

CORRECT ANSWER
Heat
EDDIE SAYS
You will learn more about why it is heat when you do the module on electricity. Essentially, the electrons bash into stuff in the wire that is not moving. This causes it to vibrate, and we all know that vibrating particles are hot particles. The more they vibrate, the more heat they have. Heat is energy loss and we want to stop that as much as possible.
  • Question 7

Describe the function of a step-down transformer. 

 

[2]

CORRECT ANSWER
EDDIE SAYS
Remember, if it is worth two marks then you need to write two things. In this case, we wanted you to state that the voltage and current change in a transformer. Did you spot that we said step-down transformer in the question? This is because you needed to specifically talk about what happens to both the voltage and the current in a step-down transformer. Read the question and be specific: Step-down = voltage goes down = current goes up.
  • Question 8

Describe the function of the National Grid. 

 

[1]

CORRECT ANSWER
EDDIE SAYS
Just as in all subjects, words are important in science. You must use the term 'transfer' and 'generate' to be able to accurately describe what the National Grid does. It transfers the energy from where it is generated to where it is needed.
  • Question 9

Compare AC and DC in terms of movement of electrons. 

 

[2]

CORRECT ANSWER
EDDIE SAYS
When it says 'compare', it means you need to state something about each of these things and then say how they are different. In this example, all you need to do is say how the electrons move in AC and DC - that is enough of a comparison. AC - from side to side. DC - constantly moving in one direction.
  • Question 10

Describe what happens to the electricity when it goes through a step-up transformer. 

 

[2]

CORRECT ANSWER
EDDIE SAYS
Aha! Did you remember which way round the step-up and step-down transformers go? Did you spot it in the question? Step-up = voltage up = current down. The direction of the transformer always refers to the voltage. Another activity completed! You're flying through these - well done!
Try it for free ---- OR ----

Get started for free so you can track and measure your child's progress on this activity.

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started
laptop

Try an activity or get started for free