Subjects
Maths
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Responding to change (a2 only)
Infection and response
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Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
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Physics
6 Dec 2025
355
3 pages
Zofia @zofia_577
Ever wonder how electricity gets from power stations to your phone charger? The mains electricity system and National... Show more
Your home's electricity supply is quite different from the direct current in batteries. Mains electricity uses alternating current (a.c.), which means the current changes direction back and forth 50 times every second - that's the frequency of 50 Hz.
In the UK, your wall sockets provide about 230 volts, which is powerful enough to run everything from your kettle to your gaming console. Unlike battery circuits with simple positive and negative terminals, mains electricity uses three different wires with specific jobs.
The live wire carries the alternating voltage to your appliances and is seriously dangerous - it's the one that can give you a fatal shock. The neutral wire completes the circuit and is much safer due to its lower voltage. Finally, the earth wire acts like a safety net, preventing appliances from becoming dangerously live if something goes wrong.
Safety tip Never mess about with mains electricity - that 230V can easily kill you, unlike the 1.5V from a AA battery!
Most cars still run on petrol or diesel from crude oil, but electric vehicles are becoming more popular. They produce zero emissions whilst driving, but remember - when you charge them, you're using electricity from the National Grid, which still gets most of its power from fossil fuels.
Biofuels offer another alternative that's renewable, though whether they're truly carbon-neutral is still debated by scientists. The big picture is that nearly 8 billion people need electricity, creating massive demand.
Unfortunately, about 84% of the world's energy still comes from non-renewable sources that pump out carbon emissions. This is why scientists are frantically developing better ways to generate clean electricity - the environmental impact is enormous.
Think about it Every time you charge your phone, you're connected to power stations that might be burning fossil fuels hundreds of miles away!
The National Grid is basically a massive network of cables, pylons and transformers that moves electricity from power stations to your home. The clever bit is how it uses transformers to make the whole system efficient.
Step-up transformers increase the voltage for long-distance transmission, which actually reduces the current and cuts down on energy waste from heating effects. Step-down transformers do the opposite - they reduce voltage and increase current for homes and factories that need higher currents.
Here's the brilliant part transformers change voltage but keep the total electrical power the same. However, they only work with alternating current - this is why we use a.c. mains electricity rather than d.c. like batteries.
The whole system means you can flick a switch and instantly access power generated possibly hundreds of miles away - pretty impressive engineering when you think about it!
Key fact Without transformers, we'd lose huge amounts of electricity as heat during transmission - they're essential for an efficient power grid!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
7
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the differences between fossil fuels and renewable energy sources in this comprehensive summary. Understand the environmental impacts, reliability, and the role of human activities in the greenhouse effect. This resource covers key concepts such as energy transition, non-renewable vs renewable energy, and electricity generation, making it essential for Year 9 Physics students.
PhysicsExplore the key concepts of energy resources, including fossil fuels, renewable energy, and energy efficiency. This summary covers advantages and disadvantages of various energy sources, equations for energy calculations, and practical investigations related to thermal insulation and energy transfer. Ideal for GCSE Physics students preparing for AQA Higher Triple exams.
PhysicsDive into the fundamentals of renewable energy, covering key sources such as solar, wind, geothermal, and biomass. This summary highlights advantages, disadvantages, and the future of energy consumption trends. Ideal for students seeking to understand sustainable energy solutions and their impact on the environment.
PhysicsDive into the advantages and disadvantages of various energy sources, including renewable options like biofuels, wind, and solar power, as well as non-renewable resources such as fossil fuels and nuclear energy. This summary covers energy efficiency, energy transfers, and the impact of each source on the environment, making it essential for understanding energy systems and sustainability.
PhysicsExplore key principles of energy, including kinetic and potential energy, conservation of energy, and various energy resources. This summary covers essential equations, energy transformations, and the efficiency of energy use, tailored for GCSE Physics students. Ideal for exam preparation and understanding fundamental energy concepts.
PhysicsExplore the fundamentals of nuclear reactions, including fission and fusion processes, radiation types, and their applications in medicine and industry. This summary covers key concepts such as neutron absorption, chain reactions, radioactive decay, and safety precautions. Ideal for GCSE Physics students preparing for exams.
PhysicsThis is the aqa exam board for triple highwe
ChemistryApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Zofia
@zofia_577
Ever wonder how electricity gets from power stations to your phone charger? The mains electricity system and National Grid work together to deliver power safely to millions of homes across the UK, using some clever engineering tricks to make it... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Your home's electricity supply is quite different from the direct current in batteries. Mains electricity uses alternating current (a.c.), which means the current changes direction back and forth 50 times every second - that's the frequency of 50 Hz.
In the UK, your wall sockets provide about 230 volts, which is powerful enough to run everything from your kettle to your gaming console. Unlike battery circuits with simple positive and negative terminals, mains electricity uses three different wires with specific jobs.
The live wire carries the alternating voltage to your appliances and is seriously dangerous - it's the one that can give you a fatal shock. The neutral wire completes the circuit and is much safer due to its lower voltage. Finally, the earth wire acts like a safety net, preventing appliances from becoming dangerously live if something goes wrong.
Safety tip: Never mess about with mains electricity - that 230V can easily kill you, unlike the 1.5V from a AA battery!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Most cars still run on petrol or diesel from crude oil, but electric vehicles are becoming more popular. They produce zero emissions whilst driving, but remember - when you charge them, you're using electricity from the National Grid, which still gets most of its power from fossil fuels.
Biofuels offer another alternative that's renewable, though whether they're truly carbon-neutral is still debated by scientists. The big picture is that nearly 8 billion people need electricity, creating massive demand.
Unfortunately, about 84% of the world's energy still comes from non-renewable sources that pump out carbon emissions. This is why scientists are frantically developing better ways to generate clean electricity - the environmental impact is enormous.
Think about it: Every time you charge your phone, you're connected to power stations that might be burning fossil fuels hundreds of miles away!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The National Grid is basically a massive network of cables, pylons and transformers that moves electricity from power stations to your home. The clever bit is how it uses transformers to make the whole system efficient.
Step-up transformers increase the voltage for long-distance transmission, which actually reduces the current and cuts down on energy waste from heating effects. Step-down transformers do the opposite - they reduce voltage and increase current for homes and factories that need higher currents.
Here's the brilliant part: transformers change voltage but keep the total electrical power the same. However, they only work with alternating current - this is why we use a.c. mains electricity rather than d.c. like batteries.
The whole system means you can flick a switch and instantly access power generated possibly hundreds of miles away - pretty impressive engineering when you think about it!
Key fact: Without transformers, we'd lose huge amounts of electricity as heat during transmission - they're essential for an efficient power grid!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
7
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the differences between fossil fuels and renewable energy sources in this comprehensive summary. Understand the environmental impacts, reliability, and the role of human activities in the greenhouse effect. This resource covers key concepts such as energy transition, non-renewable vs renewable energy, and electricity generation, making it essential for Year 9 Physics students.
PhysicsExplore the key concepts of energy resources, including fossil fuels, renewable energy, and energy efficiency. This summary covers advantages and disadvantages of various energy sources, equations for energy calculations, and practical investigations related to thermal insulation and energy transfer. Ideal for GCSE Physics students preparing for AQA Higher Triple exams.
PhysicsDive into the fundamentals of renewable energy, covering key sources such as solar, wind, geothermal, and biomass. This summary highlights advantages, disadvantages, and the future of energy consumption trends. Ideal for students seeking to understand sustainable energy solutions and their impact on the environment.
PhysicsDive into the advantages and disadvantages of various energy sources, including renewable options like biofuels, wind, and solar power, as well as non-renewable resources such as fossil fuels and nuclear energy. This summary covers energy efficiency, energy transfers, and the impact of each source on the environment, making it essential for understanding energy systems and sustainability.
PhysicsExplore key principles of energy, including kinetic and potential energy, conservation of energy, and various energy resources. This summary covers essential equations, energy transformations, and the efficiency of energy use, tailored for GCSE Physics students. Ideal for exam preparation and understanding fundamental energy concepts.
PhysicsExplore the fundamentals of nuclear reactions, including fission and fusion processes, radiation types, and their applications in medicine and industry. This summary covers key concepts such as neutron absorption, chain reactions, radioactive decay, and safety precautions. Ideal for GCSE Physics students preparing for exams.
PhysicsThis is the aqa exam board for triple highwe
ChemistryApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Sociology