Maths
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Responding to change (a2 only)
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Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
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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
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Physics
13 Dec 2025
62
3 pages
Rhea Patel @rheapatel_twzq
Electric fields are invisible force fields that surround charged objects, creating forces without any physical contact. Understanding how... Show more
Think of electric fields as invisible zones around charged objects where other charges will feel a push or pull. Coulomb's Law lets you calculate exactly how strong this force will be using the formula F = Qq/(4πε₀r²).
The direction of the force depends entirely on the types of charges involved. Opposite charges attract (giving a negative force value), whilst like charges repel (giving a positive force value). It's like magnets, but with electricity instead.
Electric field strength measures the force per unit positive charge, calculated as E = F/Q. In a radial field around a point charge, the field strength weakens as you move further away - you can actually see this because the field lines spread out more.
Quick Tip Remember that field strength follows an inverse square law - double the distance, and the field becomes four times weaker!
Uniform electric fields are like the complete opposite of radial fields - the field strength stays exactly the same everywhere. You can create one by connecting two parallel plates to opposite ends of a battery, and the field strength becomes E = V/d.
Capacitors work by storing charge on these parallel plates. Their capacitance (how much charge they can store) depends on the plate area, the distance between them, and what material sits between the plates C = ε₀A/d.
When charged particles zip through uniform fields, they follow parabolic paths - just like throwing a ball horizontally whilst gravity pulls it down. Positive particles follow the field lines, whilst negative particles go against them.
Real-world Connection This parabolic motion is exactly how old CRT televisions and computer monitors worked - electrons were steered by electric fields to hit the right spots on the screen!
Electric potential tells you the potential energy per unit charge at any point, calculated as V = Q/(4πε₀r). Think of it like electric "height" - charges naturally want to roll from high potential to low potential, just like a ball rolling downhill.
The potential is strongest right at the surface of a charge and gets weaker as you move away. Electric potential energy combines this with the actual charge present PE = Vq/(4πε₀r).
Electric fields and gravitational fields work remarkably similarly - both follow inverse square laws and use field lines. However, gravity only attracts, whilst electric forces can push or pull. Also, you can shield electric fields with conductors, but nothing blocks gravity.
Exam Success The comparison between gravitational and electric fields is a favourite exam topic - make sure you can list at least three similarities and three differences!
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.
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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the fundamental concepts of particle physics, including the structure of atoms, the classification of subatomic particles (hadrons, leptons, baryons, and mesons), and the significance of isotopes. This summary provides essential equations for calculating specific charge and examples of various particles, making it a valuable resource for A-Level physics students.
PhysicsExplore the essential concepts of particle physics, including hadrons, leptons, baryons, and mesons. This summary covers quark compositions, charge properties, and the role of exchange particles in fundamental interactions. Ideal for AQA A-level Physics students seeking a concise understanding of subatomic particles and their classifications.
PhysicsWhat are waves?
PhysicsExplore the Doppler Effect in physics, focusing on the apparent change in wavelength and frequency of waves due to relative motion. This summary covers key concepts such as the speed of light, frequency shifts, and the implications for light waves from distant galaxies. Ideal for A-level physics students.
PhysicsExplore the principles of motion, forces, and gravity in space travel. This summary covers key concepts such as Newton's Laws of Motion, projectile motion, gravitational field strength, and the mechanics of spacecraft docking. Ideal for students studying physics and space exploration.
PhysicsExplore the core concepts of particle physics, including the four fundamental forces, classification of particles, nuclear decay processes, and the role of quarks. This summary covers essential topics such as protons, neutrons, photons, and conservation laws, providing a comprehensive overview for A-level Physics students.
PhysicsQuotes 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
Rhea Patel
@rheapatel_twzq
Electric fields are invisible force fields that surround charged objects, creating forces without any physical contact. Understanding how these fields work is crucial for grasping everything from why your hair stands up after going down a plastic slide to how... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Think of electric fields as invisible zones around charged objects where other charges will feel a push or pull. Coulomb's Law lets you calculate exactly how strong this force will be using the formula F = Qq/(4πε₀r²).
The direction of the force depends entirely on the types of charges involved. Opposite charges attract (giving a negative force value), whilst like charges repel (giving a positive force value). It's like magnets, but with electricity instead.
Electric field strength measures the force per unit positive charge, calculated as E = F/Q. In a radial field around a point charge, the field strength weakens as you move further away - you can actually see this because the field lines spread out more.
Quick Tip: Remember that field strength follows an inverse square law - double the distance, and the field becomes four times weaker!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Uniform electric fields are like the complete opposite of radial fields - the field strength stays exactly the same everywhere. You can create one by connecting two parallel plates to opposite ends of a battery, and the field strength becomes E = V/d.
Capacitors work by storing charge on these parallel plates. Their capacitance (how much charge they can store) depends on the plate area, the distance between them, and what material sits between the plates: C = ε₀A/d.
When charged particles zip through uniform fields, they follow parabolic paths - just like throwing a ball horizontally whilst gravity pulls it down. Positive particles follow the field lines, whilst negative particles go against them.
Real-world Connection: This parabolic motion is exactly how old CRT televisions and computer monitors worked - electrons were steered by electric fields to hit the right spots on the screen!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Electric potential tells you the potential energy per unit charge at any point, calculated as V = Q/(4πε₀r). Think of it like electric "height" - charges naturally want to roll from high potential to low potential, just like a ball rolling downhill.
The potential is strongest right at the surface of a charge and gets weaker as you move away. Electric potential energy combines this with the actual charge present: PE = Vq/(4πε₀r).
Electric fields and gravitational fields work remarkably similarly - both follow inverse square laws and use field lines. However, gravity only attracts, whilst electric forces can push or pull. Also, you can shield electric fields with conductors, but nothing blocks gravity.
Exam Success: The comparison between gravitational and electric fields is a favourite exam topic - make sure you can list at least three similarities and three differences!
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.
1
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the fundamental concepts of particle physics, including the structure of atoms, the classification of subatomic particles (hadrons, leptons, baryons, and mesons), and the significance of isotopes. This summary provides essential equations for calculating specific charge and examples of various particles, making it a valuable resource for A-Level physics students.
PhysicsExplore the essential concepts of particle physics, including hadrons, leptons, baryons, and mesons. This summary covers quark compositions, charge properties, and the role of exchange particles in fundamental interactions. Ideal for AQA A-level Physics students seeking a concise understanding of subatomic particles and their classifications.
PhysicsWhat are waves?
PhysicsExplore the Doppler Effect in physics, focusing on the apparent change in wavelength and frequency of waves due to relative motion. This summary covers key concepts such as the speed of light, frequency shifts, and the implications for light waves from distant galaxies. Ideal for A-level physics students.
PhysicsExplore the principles of motion, forces, and gravity in space travel. This summary covers key concepts such as Newton's Laws of Motion, projectile motion, gravitational field strength, and the mechanics of spacecraft docking. Ideal for students studying physics and space exploration.
PhysicsExplore the core concepts of particle physics, including the four fundamental forces, classification of particles, nuclear decay processes, and the role of quarks. This summary covers essential topics such as protons, neutrons, photons, and conservation laws, providing a comprehensive overview for A-level Physics students.
PhysicsQuotes 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