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Dec 20, 2025
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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
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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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Improve your grades
Join milions of students
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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 specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the 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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4.9/5
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4.8/5
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user