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Electric Fields Study Notes with Diagrams
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Isabella
@isabella_qftg
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Understanding Electric Fields
Ever wondered why your hair stands up when you touch a Van de Graaff generator? That's electric fields in action! An electric field is simply a region where charged objects can attract or repel other charges - it's like an invisible force zone around any charged particle.
The gold foil experiment demonstrates this perfectly. When you charge an electroscope positively and bring it near another positive charge, they repel each other. Bring opposite charges together, and they attract. It's that simple!
Electric field strength measures how strong this invisible force is. You can calculate it three different ways: E = F ÷ Q (force per unit charge), E = V ÷ d (voltage over distance), or E = Q ÷ 4πε₀r² for point charges. The units are either V m⁻¹ or N C⁻¹ - both mean the same thing.
Quick Tip: Think of electric field strength like measuring how "pushy" the invisible force is around a charged object.
Drawing Electric Fields and Coulomb's Law
Drawing electric field lines follows four simple rules that you absolutely need to remember for exams. Lines always go from positive to negative charges, they never intersect (imagine trying to walk in two directions at once!), they flow from high to low potential, and inside conductors, the net electric field is always zero.
For a uniformly charged sphere, the field lines look like spokes on a bicycle wheel - radiating outward if positive, pointing inward if negative. This pattern is crucial for understanding how charges distribute themselves.
Coulomb's law reveals something fascinating about electric forces. When you double the distance between two charges, the force between them doesn't just halve - it drops to a quarter of its original strength! This inverse square relationship appears everywhere in physics.
Exam Focus: Remember that Coulomb's law only works for point-like charges - not extended objects like charged rods or plates.
Electric Potential and Uniform Fields
Want to create a perfectly uniform electric field? You need a uniformly charged infinite plane (or in reality, two parallel plates). Unlike the radiating field around a point charge, this creates perfectly straight, parallel field lines with constant strength.
Electric potential might sound complex, but it's just measuring energy per unit charge. Think of it like gravitational potential energy - the higher you go, the more potential energy you have. With electric charges, the further you move against the field, the more electric potential energy builds up.
When electric potential energy has a negative value, it means you'd need to do work against the electric field to separate the charges. It's like trying to pull two magnets apart - you have to fight against their natural attraction.
The formula V = k(q ÷ r) tells you the potential at any distance from a point charge, where k is Coulomb's constant (8.99 × 10⁹).
Memory Trick: Electric potential is like climbing a hill against gravity - the higher you go against the field, the more potential energy you gain.
Electric Potential Difference
Electric potential difference is what we commonly call voltage - it's the energy difference between two points in an electric field. This concept is absolutely fundamental because it drives all electrical circuits and devices you use daily.
Think of it like the height difference between two points on a hill. Just as water naturally flows from higher to lower ground, electric charges naturally move from higher to lower potential. The bigger the potential difference, the stronger the "push" on the charges.
This potential difference is defined as the work needed per unit charge to move a test charge between two points. It's what makes your phone battery work, powers your home, and creates the spark when you touch a metal door handle after walking on carpet.
Real-World Connection: Every time you plug in a device, you're using electric potential difference - the mains voltage of 230V means there's a 230-joule energy difference per coulomb of charge.
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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
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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
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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
Electric Fields Study Notes with Diagrams
I
Isabella
@isabella_qftg
Electric and magnetic fields are invisible forces that surround us everywhere, from the static shock you get touching a door handle to the way your phone charges wirelessly. Understanding these fields is crucial for A-level Physics and explains how everything... Show more
Understanding Electric Fields
Ever wondered why your hair stands up when you touch a Van de Graaff generator? That's electric fields in action! An electric field is simply a region where charged objects can attract or repel other charges - it's like an invisible force zone around any charged particle.
The gold foil experiment demonstrates this perfectly. When you charge an electroscope positively and bring it near another positive charge, they repel each other. Bring opposite charges together, and they attract. It's that simple!
Electric field strength measures how strong this invisible force is. You can calculate it three different ways: E = F ÷ Q (force per unit charge), E = V ÷ d (voltage over distance), or E = Q ÷ 4πε₀r² for point charges. The units are either V m⁻¹ or N C⁻¹ - both mean the same thing.
Quick Tip: Think of electric field strength like measuring how "pushy" the invisible force is around a charged object.
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Drawing Electric Fields and Coulomb's Law
Drawing electric field lines follows four simple rules that you absolutely need to remember for exams. Lines always go from positive to negative charges, they never intersect (imagine trying to walk in two directions at once!), they flow from high to low potential, and inside conductors, the net electric field is always zero.
For a uniformly charged sphere, the field lines look like spokes on a bicycle wheel - radiating outward if positive, pointing inward if negative. This pattern is crucial for understanding how charges distribute themselves.
Coulomb's law reveals something fascinating about electric forces. When you double the distance between two charges, the force between them doesn't just halve - it drops to a quarter of its original strength! This inverse square relationship appears everywhere in physics.
Exam Focus: Remember that Coulomb's law only works for point-like charges - not extended objects like charged rods or plates.
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Electric Potential and Uniform Fields
Want to create a perfectly uniform electric field? You need a uniformly charged infinite plane (or in reality, two parallel plates). Unlike the radiating field around a point charge, this creates perfectly straight, parallel field lines with constant strength.
Electric potential might sound complex, but it's just measuring energy per unit charge. Think of it like gravitational potential energy - the higher you go, the more potential energy you have. With electric charges, the further you move against the field, the more electric potential energy builds up.
When electric potential energy has a negative value, it means you'd need to do work against the electric field to separate the charges. It's like trying to pull two magnets apart - you have to fight against their natural attraction.
The formula V = k(q ÷ r) tells you the potential at any distance from a point charge, where k is Coulomb's constant (8.99 × 10⁹).
Memory Trick: Electric potential is like climbing a hill against gravity - the higher you go against the field, the more potential energy you gain.
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Electric Potential Difference
Electric potential difference is what we commonly call voltage - it's the energy difference between two points in an electric field. This concept is absolutely fundamental because it drives all electrical circuits and devices you use daily.
Think of it like the height difference between two points on a hill. Just as water naturally flows from higher to lower ground, electric charges naturally move from higher to lower potential. The bigger the potential difference, the stronger the "push" on the charges.
This potential difference is defined as the work needed per unit charge to move a test charge between two points. It's what makes your phone battery work, powers your home, and creates the spark when you touch a metal door handle after walking on carpet.
Real-World Connection: Every time you plug in a device, you're using electric potential difference - the mains voltage of 230V means there's a 230-joule energy difference per coulomb of charge.
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
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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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