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30 Dec 2025
•
Nat 5 Physics Unit 1: Waves & Radiation Revision
J
Jenna
@jenna_cp06
1 / 6
Wave Properties & Behaviour
Ever noticed how your voice echoes differently in a bathroom versus outside? That's waves in action! Waves transfer energy from one place to another, and they come in two main types that behave quite differently.
Transverse waves move energy perpendicular to their source - think of light waves or the waves you create by flicking a rope up and down. Longitudinal waves push energy in the same direction as the source, like sound waves travelling through air when you speak.
Every wave has five key properties you need to master: amplitude (height), wavelength (length), frequency (waves per second), period (time for one wave), and speed (distance per time). The magic happens with the equation v = f × λ, which connects speed, frequency, and wavelength.
Quick Tip: Remember that during diffraction (when waves bend around objects), the speed, frequency, and wavelength all stay the same - the wave just changes direction!
Electromagnetic Spectrum
Your mobile phone, microwave, and the Sun all have something in common - they all use electromagnetic waves that travel at an incredible 3 × 10⁸ m/s through space. These waves form a family called the electromagnetic spectrum.
From longest to shortest wavelength, we have: radio waves (communication), microwaves (cooking and phones), infrared (heat detection), visible light (what you see), ultraviolet (sun tans), X-rays (medical imaging), and gamma rays (sterilisation). Each type has different uses based on its energy level.
Visible light is the tiny portion you can actually see, ranging from red (longest wavelength) to violet (shortest wavelength). When light hits different materials, it follows the law of reflection (angle in equals angle out) or bends through refraction when changing speed between materials.
Remember: Higher frequency means higher energy - that's why gamma rays are dangerous while radio waves are safe!
Nuclear Radiation Basics
Some atoms are like wobbly chairs - they're unstable and need to release energy to become balanced. These radioisotopes achieve stability by shooting out nuclear radiation from their nucleus, and this process affects everything around them.
There are three types of radiation with very different personalities. Alpha particles are heavy and slow - they can't even get through paper but are dangerous if you swallow them. Beta particles are fast electrons that need metal foil to stop them. Gamma rays are like super-powered X-rays that need thick concrete or lead walls to block them.
When radiation hits normal atoms, it can knock electrons away, creating ions (charged atoms). This ionisation is why radiation can be both useful and dangerous - it changes the structure of whatever it touches.
Safety First: Alpha causes the most ionisation but travels the shortest distance, whilst gamma travels the furthest but causes the least ionisation per particle.
Radiation Safety & Background Sources
You're actually surrounded by background radiation right now, and that's completely normal! It comes from rocks, cosmic rays from space, building materials, and even your own body contains radioactive elements like potassium and carbon.
Man-made sources include medical treatments, X-rays, nuclear power stations, and even smoke detectors. The key is understanding that ionising radiation can damage healthy cells, potentially causing cancer, so we need to measure and control exposure carefully.
Safety with radioactive materials follows simple rules: use forceps (never bare hands), keep your distance, use proper shielding, avoid bringing sources near your eyes, and always wash hands thoroughly afterwards. Workers in nuclear industries wear badges that monitor their radiation dose to ensure they stay within safe limits.
Dose Limits: The average person in the UK receives 2.2mSv per year from background radiation, whilst radiation workers are limited to 20mSv annually.
Measuring Radiation & Medical Uses
Understanding radiation exposure involves several key measurements. Absorbed dose shows how much energy radiation deposits in your body, whilst equivalent dose considers the biological damage different radiation types cause using radiation weighting factors.
Medicine uses radiation in brilliant ways. Gamma rays can target and destroy cancer cells during treatment. Radioactive tracers help doctors diagnose problems by following their path through your body - they're chosen to concentrate in specific organs, emit detectable gamma rays, and lose radioactivity quickly for safety.
Sterilisation uses intense gamma radiation to kill bacteria on medical equipment like syringes and bandages. Nuclear power provides electricity with advantages (no greenhouse gases, very little fuel needed) but also serious disadvantages (potential accidents, radioactive waste, eventual disposal of power stations).
Half-life is crucial - it's the time for radiation activity to halve, helping us predict how long sources remain dangerous and how quickly medical tracers clear from your body.
Nuclear Reactions
Nuclear fission is like splitting a massive atomic nucleus into two smaller pieces, releasing enormous energy in the process. When a neutron hits a uranium atom, it splits and releases more neutrons, which can hit other uranium atoms in a chain reaction.
Controlled chain reactions in nuclear power stations carefully manage this process so only one neutron from each split causes another split. Uncontrolled chain reactions let all neutrons cause splits, creating the massive energy release in atomic bombs.
Nuclear fusion works oppositely - it smashes light atomic nuclei together to form heavier ones, releasing even more energy. This happens naturally in stars like our Sun, but recreating it on Earth requires creating plasma contained by incredibly strong magnetic fields.
Energy Source: Fusion could provide unlimited clean energy, but the technical challenges of containing plasma at millions of degrees make it extremely difficult and expensive to achieve.
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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.
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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
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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
Nat 5 Physics Unit 1: Waves & Radiation Revision
J
Jenna
@jenna_cp06
You're surrounded by waves every day - from the light that lets you see to the sound from your headphones and even the radiation used in medical X-rays. Understanding waves and radiation isn't just fascinating science; it's essential knowledge that... Show more
Wave Properties & Behaviour
Ever noticed how your voice echoes differently in a bathroom versus outside? That's waves in action! Waves transfer energy from one place to another, and they come in two main types that behave quite differently.
Transverse waves move energy perpendicular to their source - think of light waves or the waves you create by flicking a rope up and down. Longitudinal waves push energy in the same direction as the source, like sound waves travelling through air when you speak.
Every wave has five key properties you need to master: amplitude (height), wavelength (length), frequency (waves per second), period (time for one wave), and speed (distance per time). The magic happens with the equation v = f × λ, which connects speed, frequency, and wavelength.
Quick Tip: Remember that during diffraction (when waves bend around objects), the speed, frequency, and wavelength all stay the same - the wave just changes direction!
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Electromagnetic Spectrum
Your mobile phone, microwave, and the Sun all have something in common - they all use electromagnetic waves that travel at an incredible 3 × 10⁸ m/s through space. These waves form a family called the electromagnetic spectrum.
From longest to shortest wavelength, we have: radio waves (communication), microwaves (cooking and phones), infrared (heat detection), visible light (what you see), ultraviolet (sun tans), X-rays (medical imaging), and gamma rays (sterilisation). Each type has different uses based on its energy level.
Visible light is the tiny portion you can actually see, ranging from red (longest wavelength) to violet (shortest wavelength). When light hits different materials, it follows the law of reflection (angle in equals angle out) or bends through refraction when changing speed between materials.
Remember: Higher frequency means higher energy - that's why gamma rays are dangerous while radio waves are safe!
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Nuclear Radiation Basics
Some atoms are like wobbly chairs - they're unstable and need to release energy to become balanced. These radioisotopes achieve stability by shooting out nuclear radiation from their nucleus, and this process affects everything around them.
There are three types of radiation with very different personalities. Alpha particles are heavy and slow - they can't even get through paper but are dangerous if you swallow them. Beta particles are fast electrons that need metal foil to stop them. Gamma rays are like super-powered X-rays that need thick concrete or lead walls to block them.
When radiation hits normal atoms, it can knock electrons away, creating ions (charged atoms). This ionisation is why radiation can be both useful and dangerous - it changes the structure of whatever it touches.
Safety First: Alpha causes the most ionisation but travels the shortest distance, whilst gamma travels the furthest but causes the least ionisation per particle.
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Radiation Safety & Background Sources
You're actually surrounded by background radiation right now, and that's completely normal! It comes from rocks, cosmic rays from space, building materials, and even your own body contains radioactive elements like potassium and carbon.
Man-made sources include medical treatments, X-rays, nuclear power stations, and even smoke detectors. The key is understanding that ionising radiation can damage healthy cells, potentially causing cancer, so we need to measure and control exposure carefully.
Safety with radioactive materials follows simple rules: use forceps (never bare hands), keep your distance, use proper shielding, avoid bringing sources near your eyes, and always wash hands thoroughly afterwards. Workers in nuclear industries wear badges that monitor their radiation dose to ensure they stay within safe limits.
Dose Limits: The average person in the UK receives 2.2mSv per year from background radiation, whilst radiation workers are limited to 20mSv annually.
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Measuring Radiation & Medical Uses
Understanding radiation exposure involves several key measurements. Absorbed dose shows how much energy radiation deposits in your body, whilst equivalent dose considers the biological damage different radiation types cause using radiation weighting factors.
Medicine uses radiation in brilliant ways. Gamma rays can target and destroy cancer cells during treatment. Radioactive tracers help doctors diagnose problems by following their path through your body - they're chosen to concentrate in specific organs, emit detectable gamma rays, and lose radioactivity quickly for safety.
Sterilisation uses intense gamma radiation to kill bacteria on medical equipment like syringes and bandages. Nuclear power provides electricity with advantages (no greenhouse gases, very little fuel needed) but also serious disadvantages (potential accidents, radioactive waste, eventual disposal of power stations).
Half-life is crucial - it's the time for radiation activity to halve, helping us predict how long sources remain dangerous and how quickly medical tracers clear from your body.
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Nuclear Reactions
Nuclear fission is like splitting a massive atomic nucleus into two smaller pieces, releasing enormous energy in the process. When a neutron hits a uranium atom, it splits and releases more neutrons, which can hit other uranium atoms in a chain reaction.
Controlled chain reactions in nuclear power stations carefully manage this process so only one neutron from each split causes another split. Uncontrolled chain reactions let all neutrons cause splits, creating the massive energy release in atomic bombs.
Nuclear fusion works oppositely - it smashes light atomic nuclei together to form heavier ones, releasing even more energy. This happens naturally in stars like our Sun, but recreating it on Earth requires creating plasma contained by incredibly strong magnetic fields.
Energy Source: Fusion could provide unlimited clean energy, but the technical challenges of containing plasma at millions of degrees make it extremely difficult and expensive to achieve.
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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