Subjects
Maths
Chemistry
Biology
English Language
History
Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
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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
8 Dec 2025
272
4 pages
Freya Playford @freyaplayford_mnhy
Magnets are everywhere around us, from your phone speakers to MRI machines, and understanding how they work is... Show more
Ever wondered why some objects stick to your fridge whilst others don't? A magnet is any material that produces a magnetic field - think of Earth itself, horseshoe magnets, or simple bar magnets.
Magnetic field lines always flow from North to South poles, and the closer these lines are packed together, the stronger the magnetic field. When you see two North poles near each other, they repel because the field lines point outward from both - but opposite poles attract.
Don't confuse magnets with magnetic materials like iron, steel, nickel, and cobalt. These materials can be influenced by magnetic fields and have the potential to become magnets themselves, but they're not automatically magnetic.
Quick Tip Remember that magnetic field lines are invisible, but iron filings can help you see their patterns!
Here's something fascinating - not all magnets are created equal! Induced or temporary magnets only have magnetic properties when they're near a permanent magnet, losing their magnetism once removed.
The key difference lies in how quickly they lose their magnetic power. Magnetically hard materials like steel hold onto their magnetism stubbornly, whilst magnetically soft materials like iron and nickel lose it rapidly.
Electromagnetism changes everything by using electric current to create magnetic fields. The right-hand rule helps you work out field direction - curl your fingers in a fist with your thumb out, point your thumb along the current direction, and your curled fingers show the magnetic field direction.
Pro Tip Electromagnets can be switched on and off, making them incredibly useful in everyday devices!
Want to supercharge an electromagnet? You've got several options that work brilliantly. Increase the current flowing through the wire, add more coils (whilst keeping the same length), or decrease the length whilst maintaining the number of turns.
The real game-changer is adding an iron core - this soft magnetic material becomes an induced magnet and dramatically boosts the electromagnetic strength. Densely packed coils create the most powerful effects.
The motor effect occurs when a current-carrying wire sits in a magnetic field, experiencing a force. Use the left-hand rule to find this force direction second finger points along the magnetic field, middle finger follows the current, and your thumb shows the force direction.
Electric motors work by changing the current direction every half turn, keeping the coil spinning continuously in the same direction - that's the magic behind countless devices you use daily.
Mind-Blowing Fact Electric motors convert electrical energy into mechanical motion, powering everything from hair dryers to electric cars!
The split ring commutator is the clever component that makes motors work smoothly. It swaps positive and negative connections every half turn, ensuring the current direction changes but the coil keeps rotating in the same direction.
To speed up motor rotations, you can increase the current, use stronger magnets (higher magnetic flux density), or add more turns to the coil. It's like fine-tuning a racing car's engine!
The generator effect (electromagnetic induction) works in reverse - instead of using electricity to create motion, you use motion to create electricity. Move a wire through a magnetic field, and you'll induce a potential difference that can power circuits.
This principle powers everything from bicycle dynamos to massive power station generators. Moving the wire faster or using stronger magnetic fields increases the voltage generated.
Real-World Connection Every time you ride a bike with lights powered by wheel rotation, you're experiencing electromagnetic induction in action!
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.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp 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
Freya Playford
@freyaplayford_mnhy
Magnets are everywhere around us, from your phone speakers to MRI machines, and understanding how they work is crucial for grasping modern technology. This topic covers everything from basic magnetic fields to how electric motors spin and generators create electricity.
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ever wondered why some objects stick to your fridge whilst others don't? A magnet is any material that produces a magnetic field - think of Earth itself, horseshoe magnets, or simple bar magnets.
Magnetic field lines always flow from North to South poles, and the closer these lines are packed together, the stronger the magnetic field. When you see two North poles near each other, they repel because the field lines point outward from both - but opposite poles attract.
Don't confuse magnets with magnetic materials like iron, steel, nickel, and cobalt. These materials can be influenced by magnetic fields and have the potential to become magnets themselves, but they're not automatically magnetic.
Quick Tip: Remember that magnetic field lines are invisible, but iron filings can help you see their patterns!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Here's something fascinating - not all magnets are created equal! Induced or temporary magnets only have magnetic properties when they're near a permanent magnet, losing their magnetism once removed.
The key difference lies in how quickly they lose their magnetic power. Magnetically hard materials like steel hold onto their magnetism stubbornly, whilst magnetically soft materials like iron and nickel lose it rapidly.
Electromagnetism changes everything by using electric current to create magnetic fields. The right-hand rule helps you work out field direction - curl your fingers in a fist with your thumb out, point your thumb along the current direction, and your curled fingers show the magnetic field direction.
Pro Tip: Electromagnets can be switched on and off, making them incredibly useful in everyday devices!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Want to supercharge an electromagnet? You've got several options that work brilliantly. Increase the current flowing through the wire, add more coils (whilst keeping the same length), or decrease the length whilst maintaining the number of turns.
The real game-changer is adding an iron core - this soft magnetic material becomes an induced magnet and dramatically boosts the electromagnetic strength. Densely packed coils create the most powerful effects.
The motor effect occurs when a current-carrying wire sits in a magnetic field, experiencing a force. Use the left-hand rule to find this force direction: second finger points along the magnetic field, middle finger follows the current, and your thumb shows the force direction.
Electric motors work by changing the current direction every half turn, keeping the coil spinning continuously in the same direction - that's the magic behind countless devices you use daily.
Mind-Blowing Fact: Electric motors convert electrical energy into mechanical motion, powering everything from hair dryers to electric cars!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The split ring commutator is the clever component that makes motors work smoothly. It swaps positive and negative connections every half turn, ensuring the current direction changes but the coil keeps rotating in the same direction.
To speed up motor rotations, you can increase the current, use stronger magnets (higher magnetic flux density), or add more turns to the coil. It's like fine-tuning a racing car's engine!
The generator effect (electromagnetic induction) works in reverse - instead of using electricity to create motion, you use motion to create electricity. Move a wire through a magnetic field, and you'll induce a potential difference that can power circuits.
This principle powers everything from bicycle dynamos to massive power station generators. Moving the wire faster or using stronger magnetic fields increases the voltage generated.
Real-World Connection: Every time you ride a bike with lights powered by wheel rotation, you're experiencing electromagnetic induction in action!
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.
3
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp 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