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1l the quest for political stability: germany, 1871-1991
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Xin Ying Pua
29/11/2025
Physics
ALEVEL PHYSICS Conduction of Electricity
221
•
29 Nov 2025
•
Electricity is all about the movement of charged particles, specifically... Show more
Electric charge is measured in coulombs (C), though we often think of it in terms of electron charges. A single electron carries a charge of 1.6 × 10⁻¹⁹ C, which means you'd need approximately 6.3 × 10¹⁸ electrons to produce just one coulomb of charge!
Not all materials allow charge to flow. Conductors (like metals) permit the movement of charge, while insulators prevent it. When we want to measure how quickly charge is flowing, we use current, which is the rate of flow of charge. The formula for current is:
Current (A) = Change in charge (C) / Change in time (s)
or mathematically: I = ΔQ/Δt
Remember this! The distinction between conductors and insulators is crucial - conductors have free electrons that can move, while insulators keep electrons firmly in place.
Metals make excellent conductors because they contain positive ions and free delocalised electrons due to metallic bonding. When you connect a battery to a metal wire, creating a potential difference, these free electrons drift from the negative terminal toward the positive terminal. This coordinated movement of charged particles is what creates an electric current.
When electrons move through a conductor, they don't travel instantly - they have a measurable drift velocity. Think of it as the average speed at which electrons travel through the material. The time taken for electrons to travel along a section of conductor equals the length divided by this drift velocity .
The number of free electrons within a section of conductor can be calculated using the formula N = ALn, where A is the cross-sectional area, L is the length, and n is the charge carrier density (the number of free electrons per cubic meter).
Current is essentially a measure of how many electrons pass through a point in the conductor per second, multiplied by each electron's charge. This gives us the important relationship:
I = nAve
where I is current, n is charge carrier density, A is cross-sectional area, v is drift velocity, and e is the electron charge.
Making connections: The formula I = nAve shows that current increases with larger cross-sectional area, higher electron density, or faster drift velocity - like how water flows faster through a wider pipe or when pushed harder.
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.
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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
Electricity is all about the movement of charged particles, specifically electrons. This section explores the fundamentals of electric charge, current, and how electrons behave in conductors - essential concepts that form the building blocks of electrical theory and applications.
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Electric charge is measured in coulombs (C), though we often think of it in terms of electron charges. A single electron carries a charge of 1.6 × 10⁻¹⁹ C, which means you'd need approximately 6.3 × 10¹⁸ electrons to produce just one coulomb of charge!
Not all materials allow charge to flow. Conductors (like metals) permit the movement of charge, while insulators prevent it. When we want to measure how quickly charge is flowing, we use current, which is the rate of flow of charge. The formula for current is:
Current (A) = Change in charge (C) / Change in time (s)
or mathematically: I = ΔQ/Δt
Remember this! The distinction between conductors and insulators is crucial - conductors have free electrons that can move, while insulators keep electrons firmly in place.
Metals make excellent conductors because they contain positive ions and free delocalised electrons due to metallic bonding. When you connect a battery to a metal wire, creating a potential difference, these free electrons drift from the negative terminal toward the positive terminal. This coordinated movement of charged particles is what creates an electric current.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When electrons move through a conductor, they don't travel instantly - they have a measurable drift velocity. Think of it as the average speed at which electrons travel through the material. The time taken for electrons to travel along a section of conductor equals the length divided by this drift velocity .
The number of free electrons within a section of conductor can be calculated using the formula N = ALn, where A is the cross-sectional area, L is the length, and n is the charge carrier density (the number of free electrons per cubic meter).
Current is essentially a measure of how many electrons pass through a point in the conductor per second, multiplied by each electron's charge. This gives us the important relationship:
I = nAve
where I is current, n is charge carrier density, A is cross-sectional area, v is drift velocity, and e is the electron charge.
Making connections: The formula I = nAve shows that current increases with larger cross-sectional area, higher electron density, or faster drift velocity - like how water flows faster through a wider pipe or when pushed harder.
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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Explore the principles of electric current, including charge flow, drift velocity, and the relationship defined by I = nAve. This summary covers key concepts such as charge carrier density, the role of free electrons in conductors, and the calculation of current in electrical circuits. Ideal for A-Level Physics students.
PhysicsExplore detailed solutions for the OCR A Level Physics Paper 2 from November 2021. This resource covers key concepts such as capacitors, wave properties, electric circuits, and nuclear physics, providing step-by-step explanations and calculations for each question. Ideal for students preparing for exams and seeking to enhance their understanding of complex physics topics.
PhysicsExplore detailed solutions to the OCR A Level Physics Paper 3 from June 2017. This resource covers key concepts such as Ohm's Law, RC circuits, elastic potential energy, tension forces, simple harmonic motion, circuit analysis, capacitors, magnetic fields, and more. Ideal for students preparing for exams, this comprehensive guide provides step-by-step explanations and calculations for each question.
PhysicsExplore the essential SI units and measurement systems in physics, including mass, electric potential, and dimensional analysis. This summary covers key concepts relevant for A Level Physics, providing a clear understanding of physical quantities and their applications.
PhysicsExplore the fundamentals of power in electrical circuits, including key formulas (P = E/t, P = VI) and the differences between series and parallel configurations. This summary covers energy transfer, voltage distribution, and current behavior in various circuit setups, making it essential for A-Level Physics students.
PhysicsExplore detailed solutions for the OCR A Level Physics June 2022 Paper 2. This resource covers key concepts such as radioactive decay, electric circuits, electromagnetic induction, and the photoelectric effect. Ideal for exam preparation and understanding complex physics principles.
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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