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Aliki ๐ฉต
08/12/2025
Physics
Physics: Magnetism, Electromagnetism, EM Induction
77
โข
8 Dec 2025
โข
Understanding Physics: Magnetism and Electromagnetic Principles
Aliki ๐ฉต
@study_wabbit
1 / 3
Understanding Magnetism
Magnetic poles work exactly like you'd expect - opposites attract and like poles repel each other. Every magnet has a north pole and south pole , and these are opposite to Earth's magnetic poles.
Materials fall into two categories when it comes to magnetism. Soft magnetic materials like iron are dead easy to magnetise and demagnetise, making them perfect for electromagnets and speakers. Hard magnetic materials like steel are much tougher to magnetise but hold onto their magnetism brilliantly - that's why they're used in compass needles and permanent magnets.
The magnetic field is the invisible area around a magnet where magnetic forces can act. You can actually see this field using iron filings or a compass! The field lines always run from north to south, never cross each other, and bunch up closer together at the poles where the magnetic force is strongest.
Quick Tip: Remember that magnetic field lines are like invisible highways that show exactly where and how strong the magnetic force is - the closer the lines, the stronger the pull!
Electromagnetism and Motors
Here's where things get really clever - when electricity flows through a wire, it creates a magnetic field around that wire. The direction follows the right-hand rule: thumb points along current direction, fingers curl around showing the magnetic field direction.
The motor effect is basically how we turn electrical energy into movement. When you put a current-carrying wire into a magnetic field at right angles, it experiences a force that makes it move. Fleming's left-hand rule tells you which way it'll move: thumb shows motion, first finger shows field direction, middle finger shows current direction.
DC motors use this principle with coils of wire spinning between magnets. The commutator is the clever bit that switches the current direction to keep the motor spinning in one direction. Want a stronger motor? Use more coils, stronger magnets, or increase the current.
Electromagnets are just solenoids (coils) with an iron core inside. When current flows through the coil, the iron becomes magnetised and acts like a bar magnet. These power everything from loudspeakers to doorbells by switching the magnetism on and off.
Real-World Connection: Your phone's speaker uses electromagnets - alternating current makes the coil oscillate back and forth, moving the cone that creates the sound waves you hear!
Electromagnetic Induction and Transformers
Electromagnetic induction is the reverse of motors - instead of using electricity to create movement, you use movement to create electricity. Move a wire through a magnetic field (or change the magnetic field through a coil) and you'll induce a voltage. It's that simple!
This is how generators work at power stations - they use Fleming's right-hand rule . Mechanical energy from steam turbines or wind gets converted into electrical energy that powers your home.
Transformers are absolutely crucial for getting electricity from power stations to your house safely. They use electromagnetic induction to change voltages - step-up transformers increase voltage for efficient long-distance transmission, whilst step-down transformers reduce it to safe household levels (230V).
The transformer equation is dead useful: Vp/Vs = Np/Ns . More turns in the secondary coil means higher output voltage, and vice versa.
Why It Matters: Without transformers, we couldn't have a national electricity grid - the voltage needs to be stepped up to 400,000V for efficient transmission, then stepped back down for safe home use!
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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 itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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
Understanding Physics: Magnetism and Electromagnetic Principles
Aliki ๐ฉต
@study_wabbit
Ever wonder how your earbuds produce sound or why compass needles always point north? Magnetism and electromagnetism are the invisible forces behind loads of everyday tech, from electric motors in cars to the transformers that get electricity to your home.
Understanding Magnetism
Magnetic poles work exactly like you'd expect - opposites attract and like poles repel each other. Every magnet has a north pole and south pole , and these are opposite to Earth's magnetic poles.
Materials fall into two categories when it comes to magnetism. Soft magnetic materials like iron are dead easy to magnetise and demagnetise, making them perfect for electromagnets and speakers. Hard magnetic materials like steel are much tougher to magnetise but hold onto their magnetism brilliantly - that's why they're used in compass needles and permanent magnets.
The magnetic field is the invisible area around a magnet where magnetic forces can act. You can actually see this field using iron filings or a compass! The field lines always run from north to south, never cross each other, and bunch up closer together at the poles where the magnetic force is strongest.
Quick Tip: Remember that magnetic field lines are like invisible highways that show exactly where and how strong the magnetic force is - the closer the lines, the stronger the pull!
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Electromagnetism and Motors
Here's where things get really clever - when electricity flows through a wire, it creates a magnetic field around that wire. The direction follows the right-hand rule: thumb points along current direction, fingers curl around showing the magnetic field direction.
The motor effect is basically how we turn electrical energy into movement. When you put a current-carrying wire into a magnetic field at right angles, it experiences a force that makes it move. Fleming's left-hand rule tells you which way it'll move: thumb shows motion, first finger shows field direction, middle finger shows current direction.
DC motors use this principle with coils of wire spinning between magnets. The commutator is the clever bit that switches the current direction to keep the motor spinning in one direction. Want a stronger motor? Use more coils, stronger magnets, or increase the current.
Electromagnets are just solenoids (coils) with an iron core inside. When current flows through the coil, the iron becomes magnetised and acts like a bar magnet. These power everything from loudspeakers to doorbells by switching the magnetism on and off.
Real-World Connection: Your phone's speaker uses electromagnets - alternating current makes the coil oscillate back and forth, moving the cone that creates the sound waves you hear!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Electromagnetic Induction and Transformers
Electromagnetic induction is the reverse of motors - instead of using electricity to create movement, you use movement to create electricity. Move a wire through a magnetic field (or change the magnetic field through a coil) and you'll induce a voltage. It's that simple!
This is how generators work at power stations - they use Fleming's right-hand rule . Mechanical energy from steam turbines or wind gets converted into electrical energy that powers your home.
Transformers are absolutely crucial for getting electricity from power stations to your house safely. They use electromagnetic induction to change voltages - step-up transformers increase voltage for efficient long-distance transmission, whilst step-down transformers reduce it to safe household levels (230V).
The transformer equation is dead useful: Vp/Vs = Np/Ns . More turns in the secondary coil means higher output voltage, and vice versa.
Why It Matters: Without transformers, we couldn't have a national electricity grid - the voltage needs to be stepped up to 400,000V for efficient transmission, then stepped back down for safe home use!
We thought youโd 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 โ all at your fingertips.
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Most popular content: Faraday's Law of Induction
Most popular content in Physics
Most popular content
English - inspector calls quotes and analysis
Quotes from every main character
English Literature10
Can't find what you're looking for? Explore other subjects.
Students love us โ and so will you.
4.9/5
App Store
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
Best app on earth! no words because itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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