All the different types of waves are organised on a scale known as the electromagnetic spectrum. This includes radio waves and gamma rays. The spectrum also explains how devices work that we use daily - such as mobile phones and microwaves - and why X-rays are used in hospitals.
This article is designed for GCSE students revising for their exams, including the AQA exam board. We will cover the different parts of the electromagnetic spectrum and their uses. Examples and quiz questions are included to test your knowledge. If you need 1-2-1 support studying this topic and making revision notes, TeachTutti has a list of qualified GCSE Science tutors who can support your learning.
Types of electromagnetic waves
The EM spectrum has a variety of wave types. Each wave has unique properties that makes it useful in a particular situation. The waves are organised by increasing frequency and decreasing wavelength. The main wave types are listed below:
Radiowaves
Radiowaves are at the lowest frequency end of the EM spectrum. It has the longest wavelengths and is mainly used for communication e.g. radio broadcasts, TV signals and mobile phones. Radio waves can travel long distances and pass through buildings. This makes them perfect for broadcasting, telecommunications and even communication with spacecraft.
Microwaves
Microwaves have shorter wavelengths and are used to cook food (hence the name "microwave"). Microwaves are ideal for satellite-based communication systems because they can pass through the atmosphere without much interference. We also use them for weather radar systems.
Infrared waves
Infrared waves have shorter wavelengths than microwaves and radiowaves. They can detect heat and are commonly found in termjal cameras, night-vision devices and remote controls. When you stand close to a fire or heater, you will feel infrared waves as heat. We also use infrared technology in medical treatments and optical fibre communication.
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Why are microwaves commonly used?
Visible light
Visible light is unique as it is the only wave on the EM spectrum seen with the naked eye. It is composed of red, orange, yellow, green, blue, indigo and violet. Each colour represents a different wavelength of light - red is the longest wavelength and violet is the shortest.
We use visible light for much of life, including vision, photography and photosynthesis. It is also used in optical fibre communication, where pulses of light are sent through thin glass fibres to transmit data over huge distances at incredible speeds. It is crucial for internet connections.
You can remember the colours in visible light with the mnemonic "Richard Of York Gave Battle In Vain"
Ultraviolet waves
Ultraviolet waves have short wavelengths and can't be seen by the human eye. UV radiation is unusual because it helps the body create vitamin D but can also cause sunburn. For example, overexposure can damage skin cells and increase the risk of skin cancer.
UV waves are widely used in a variety of fields, including spotting forged banknotes, sterilising medical equipment and hardening dental fillings. They are also used in UV lights to make materials glow, such as in nightclubs and bowling alleys. This is called "fluorescence".
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What danger can result from ultraviolet radiation?
X-Rays
X-rays have short wavelengths and carry more energy than ultraviolet waves. They are used in medicine where they pass through soft tissue but are absorbed by denser material like bones. This means they are ideal for creating images of bones and internal structures, where they can help diagnose fractures.
X-rays can be dangerous if used excessively due to their high energy. Medical professionals will take precautions, wearing protective clothing or using shields when taking images.
Gamma rays
Gamma rays is the wave with the shortest wavelength and the most energy. They are used in medical treatments as they can penetrate most materials e.g. they target and kill cancerous cells in cancer therapy. They can also sterilise medical equipment and kill bacteria in food, extending the shelf life of the product.
If you have watched science fiction, it won't come as a surprise that gamma rays are also extremely dangerous. Your cells will suffer severe damage if you're overexposed, potentially leading to cancer or death. Strict measures are enforced over its use in medical and industrial settings.
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What is the medical benefit of X-rays?
Dispersion
Dispersion happens when white light - such as sunlight - passes through a prism and splits into its component colours. This happens because each colour in visible light, such as red or blue, has a different wavelength. This means it bends or refracts by a different amount when it passes through the prism. The colour red refracts the least while violet bends the most, creating a rainbow effect. Dispersion is the same process that causes rainbows to appear when sunlight passes through water droplets after there has been a shower.
You will always see dispersion displayed as an experiment in GCSE Science. Teachers will normally show how visible light behaves by passing light through a prism. Dispersion underpins much optical technology, such as lenses and cameras. Follow the link to read Wikipedia's article on dispersion for more information.
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What causes white light to split into different colours?
Uses of EM waves
We can't see most of them but electromagnetic waves are everywhere. They are also indispensable to our everyday lives, from food to the internet.
Radio waves let us send and receive information over long distances. Examples of communication include listening to the radio, using your mobile phone, or watching television. They can pass through the atmosphere - including buildings - which makes them ideal for broadcasting and telecommunications. We even find radiowaves in space, where they communicate with spacecraft and enable us to explore the solar system.
Microwaves are commonly used in cooking as they contain far more energy. They cause water molecules to vibrate and heat the food. Their usage extends beyond the kitchen as they are essential in communicating with satellites and sending signals to and from space. They also work with radar systems to track weather patterns.
Infrared waves are synonymous with heat. Anything that gives off heat creates infrared radiation e.g. a fire or even your body. It is used in thermal imaging cameras to visualise heat in poor visibility. This makes it invaluable for search and rescue operations. Infrared technology is also present in remote controls.
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Which wave do we use in thermal imaging cameras?
Dangers of electromagnetic radiation
There are dangers to using some of the EM waves that we have to bear in mind when using them. This is particularly the case with the higher-energy parts of the spectrum:
- Ultraviolet radiation is unseen to the naked eye yet crucial to our daily lives. It helps our bodies to produce vitamin D and maintain healthy bones. However, we can damage the skin if we are exposed too much to UV radiation. This includes sunburn, though it can lead to more serious consequences, including premature skin ageing and skin cancer. Always remember to wear sunscreen and protective clothing when spending time in the sun.
- X-rays and gamma rays carry a lot of energy. This makes them dangerous in large doses. Medical practices use X-rays to take images of the human body as they can pass through tissue but not bone. If a person is frequently exposed to X-rays, it can damage living cells, however. This is why medical professionals wear lead aprons or step behind protective screens as they are often working with x-rays.
- Gamma radiation is the most powerful EM waves - they can penetrate nearly anything. This makes them invaluable for killing cancer cells in radiation therapy. It also means they risk severe damage to healthy cells if they aren't controlled. Always ensure you have sufficient protection when working with gamma rays to avoid exposure.
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How can you protect your body from UV radiation?
Conclusion - Electromagnetic spectrum revision
Every wave on the EM spectrum is unique and applied in particular ways by the natural world and modern technology. From gamma rays used in treating cancer to the radio waves that enable communication across the globe, the spectrum showcases the versatility and usability of electromagnetic radiation.
To test your understanding of the electromagnetic spectrum, try to practice past exam questions. Save My Exams has online worksheets on EM Waves to challenge you with a range of questions. If you need more help getting to grips with this or related topics, TeachTutti has a list of DBS-checked and experienced GCSE Science tutors for online and in-person tuition.
