The electromagnetic spectrum, or EM spectrum, governs our modern day lives. We can barely imagine life without it. The light we use to see, the microwaves that allow us to use our cells phones, the radio waves used to broadcast music to our cars and the gamma rays used to treat cancer, are all the same waves varying only by wavelength and frequency. The EM spectrum has far-reaching uses that have changed the way we live. Alongside this they also come with some hazards. Gamma rays have the most energy and can cause cancer, but there are plenty of other types of radiation that can harm humans.
Electromagnetic Spectrum Lesson Plans, Student Activities and Graphic Organizers
Have your students put key vocabulary into practice. One of the things students can find really difficult is using scientific vocabulary correctly and in the appropriate context. Using a visual representation or visual examples as well as a written one can really help students understand abstract concepts.
Example EM Spectrum Vocabulary
Frequency is the number of waves to pass a point every second, measured in Hertz (Hz).
Wavelength is the length of one wave, measured in meters (m).
How fast a wave travels is called wave speed, measured in meters per second (m/s). All EM waves travel at the speed of light in a vacuum.
Amplitude is the height of a wave, measured in meters (m). The higher the amplitude, the higher the intensity of the wave.
A wave that can remove electrons from an atom, thus making them an ion, is said to be ionizing.
Discussion storyboards are a great way to get your students talking about their ideas in Science. They allow students to critique and evaluate different viewpoints without upsetting other students. This activity can be used at the start of the topic to elicit any misconceptions students may have.
At first, show students a discussion storyboard like the one below. Ask them to look at the problem on the discussion storyboard. It shows four students who all have an idea about the problem in front of them. Students should think about whom they think is the most correct and be prepared to explain why that person is correct. Students might support their position by creating visuals, including text and images, on Storyboard That. These visuals can easily be exported as PowerPoint slides. After students have prepared their argument, have your students discuss their ideas. This discussion can be carried out in a range of different formats. Students could discuss in pairs, small groups or even in a teacher-led, whole class setting. It is important to agree on a list of discussion rules with students before they start so that everybody gets a chance to participate. Students will also be able to practice adapting their speech to a formal debating context and can demonstrate their grasp of formal English.
Here are some other ideas to use these discussion storyboards in your lessons.
Students add another cell on the end of the example you’ve given them to explain whom they think is correct and why.
Students create a storyboard to describe why a student is incorrect, and then "teach" the concept.
Students create their own discussion storyboards to share with peers on the current topic.
Note that the template in this assignment is blank. After clicking "Copy Assignment", add your desired problem and solutions to match the needs of your students.
(These instructions are completely customizable. After clicking "Copy Assignment", change the description of the assignment in your Dashboard.)
Read the discussion storyboard that shows four students who all have an idea about the problem in front of them. You are going to give your opinion on whom you think is correct and explain why. You will use your created storyboard to engage in discussion with your peers.
Click "Use this Template" from the assignment.
Add another cell at the end of the row.
Use text and images to explain whom you think is correct and why.
Save and submit the assignment. Make sure to use the drop-down menu to save it under the assignment title.
This is a great way for students to organize all their ideas into one place. Storyboard That with Photos for Class allows students to gather image from a wide range of resources and combine them with text in seconds
An easy way to remember the order that the different radiation types are called is using a mnemonic. One of these is “Red monkeys in vans use x-ray glasses”. A fun activity can be getting your students to come up with their own. You can adapt this activity and allow students to do this by adding a description box underneath the cells and writing their mnemonic words in there.
This activity can easily be differentiated and modified for your students by removing rows and deleting or adding information. You could even cut up the example chart and get your students to put it together like a jigsaw puzzle. Alternatively, you could have a student or small group complete a column each, then combine the columns to make a complete spectrum.
This is a nice way to produce a very valuable, student centered study resource. Students are much more likely to use and understand resources that they have created themselves. Have your students print them off and use them when reviewing the EM spectrum.
On the example given the orders of magnitude for the frequencies and wavelengths of the different parts of the spectrum have already been entered. You may want to change this so students write the ranges in. The issue with this is that often the different radiation parts overlap, and students may find that the numbers found for the ranges vary from website to website.
In this activity students will look how some of these different EM waves were discovered. This activity will get your students hooked on learning about some of the great stories about scientific discovery.
William Herschel was a famous British Scientist who is most famous for discovering the planet Uranus. He also discovered infrared radiation. Herschel carried out an experiment where he measured the temperature of the different colors of light. He found that the temperature increases as he moved the thermometer from blue to red. He them moved the thermometer just beyond the red to somewhere he thought was no light. He found it was even hotter. He concluded that there must be something there that the eyes cannot see. It was the first time humans realized that there exists a type of light that we cannot see.
Additional Key EM Spectrum Discoveries
Johann Ritter and UV
Wilhelm Röntgen and X-rays
Paul Villard and gamma rays
Isaac Newton’s experiments with the nature of colored light
Have students show their understanding of how ideas of the EM spectrum have changed over time using this timeline activity. You can use this activity to highlight how science needs scientists to collaboratively work together to share findings to further human understanding. You can also highlight how scientific discoveries can directly benefit the human race and lead to important inventions.
Ibn al-Haytham - 1015
Ibn Al-Haytham was an early Islamic scientist who was born in Basra in modern day Iraq. He discovered that light travels in straight lines. He discovered this by completing a number of experiments reflecting and refracting light.
William Herschel - 1800
William Herschel was measuring the temperature of the different colors of the EM spectrum. He found the temperature was hotter just outside the red part of spectrum. He had discovered infrared radiation.
Johann Ritter - 1801
A year after Herschel’s monumental discovery that there was a type of light the couldn’t be seen, Ritter looked a the other end of the spectrum. He found that silver chloride turned black fastest outside the violet part of the spectrum.
Heinrich Hertz - 1886
Heinrich Hertz was the first person to send and receive radio waves. He spent a lot of time trying to prove James Clerk Maxwell’s theory of electromagnetism with a spark gap transmitter.
Wilhelm Röntgen - 1895
In 1895, Wilhelm Röntgen discovered a new type of radiation. As it was unknown, he called new rays ‘X’. While experimenting with them, he created an image on a screen which showed his bones. This was the first medical X-ray taken. Later on he used his newly discovered X-rays to create an image on a photographic plate of his wife’s hand. When she saw the image, she was so surprised she shouted out, “I have seen my death!”
Paul Villard - 1900
Villard was experimenting with radiation produced by radon gas. When he put a sheet of lead in from of the radon, he found it only stopped one type of radiation and found that two others travelled through the lead. He identified this first type of radiation as alpha rays. The second type of radiation he found could be deflected by a magnetic field, he identified these as beta rays. The last type of radiation was highly penetrating. Rutherford named these new rays gamma rays.
The electromagnetic spectrum is a way of organizing the different types of EM radiation we find in the universe. It is a continuous spectrum, meaning where one part finishes, another starts with no gaps. The parts of the EM spectrum all have one thing in common: they all travel at the same speed in a vacuum. All the waves travel at 3 x 108m/s or 300,000,000 m/s. The different parts all have different uses and dangers which are related to their wavelength and frequency. As the frequency increases (and the wavelength decreases) the energy of the waves increase. The frequency and wavelength of the waves are related using v=fλ, where v is the velocity measured in m/s, f is the frequency measure in Hertz, and λ is the wavelength measured in m.
Mnemonic Device for the Types of Electromagnetic Radiation
Radio Waves have the longest wavelength, the lowest frequency, and the lowest energy. Radio waves are used for broadcasting and communication. There are no real dangers associated with radio waves as their energy is so low. Heinrich Hertz discovered radio waves and used them to show that James Clerk Maxwell’s theory of electromagnetism was correct.
Microwaves have the second longest wavelength. They are most commonly known for their use in microwave ovens. Microwave ovens work by making the water molecules in your food vibrate. The microwave oven was invented by Percy Spence and the first commercial microwave oven was made in 1947. The original microwave ovens cost $5,000! Microwaves are also used in mobile phones allowing us to communicate with people all around the world. Microwaves can be dangerous. If you were to put a person in a microwave oven, it would heat the water molecules inside the body and cook the internal tissues.
Infrared is what we, as humans, feel as warmth or heat. It is used in thermal imaging. The police use it at night to find people who are hiding. Even though the fugitive isn’t reflecting any visible light, they will still give off infrared. Infrared is also used in optical fiber communication. Optical fiber communication is when information is send down long optical cables using infrared by bouncing the signal of the sides of the fiber. Too much infrared can cause burns to your skin.
Visible Light is the narrow range of EM radiation that we can see. White light is made up 7 colors: red, orange, yellow, green, blue, indigo, violet. We can use a prism to split light into its constituent colors because the different wavelengths refract different amounts, splitting light like this is called dispersion. A good way to remember this is to think of the letters making a name - Roy G. Biv. For most of human history, visible light was the only type of radiation we thought existed before Herschel’s discovery of infrared. Visible light has a range of uses, including optical telescopy and optical microscopy. There are no real dangers associated with it, but too much visible light can damage the eye.
Ultraviolet was discovered by Johann Ritter a year after the discovery of infrared. He carried out an experiment where he measured how quickly silver chloride turned from white to black when exposed to different colors of light. Ritter found that the silver chloride turned black the fastest just passed the violet in the invisible part of the spectrum. We now know this as UV radiation. UV is the radiation that causes skin to tan and is used in tanning beds. It is also used to check for counterfeit bills: using a special type of ink that absorbs UV and emits visible light patterns can be printed on the bills that appear to glow when put under a UV lamp. Cashiers can check bills to see if they have these markings. UV can also be used to sterilize drinking water as it can kill harmful microorganisms by disrupting their DNA. High exposure to UV can also lead to an increased risk of skin cancer, which is why physicians recommend that we wear sunscreen on sunny days.
X-rays were discovered by Wilhelm Röntgen and were originally called X-rays because they were of an unknown origin, just as in math the unknown variable is often called ‘x’. They are commonly used for imaging in medicine and security. X-rays are very penetrating which means they are difficult to stop; this allows them to be used for creating images of bones. They are only absorbed by dense material like bone and metal and can easily travel through soft tissue. They are also used in airport security, allowing security officers to check the inside of a passenger's luggage without having to open the suitcase. X-rays are ionizing and they can cause cancer. This is why radiographers in hospitals will stand behind a screen or leave the room when they take an X-rays.
Gamma rays are the highest energy EM waves. They have the shortest wavelength and the highest frequency. They are extremely ionizing and penetrating. They can be very hazardous to human health and are linked to the development of cancer. As well as being a cause of cancer they can also be used to treat cancer. This may come across as counter-intuitive: "How can a type of radiation cause and treat cancer?" The answer to this, in short, is that gamma rays damage cells, when this happens to healthy cells this can cause them to change and it could cause cancer. When cancerous cells are exposed to gamma radiation, they are also damaged and can be killed. This can help stop the spread of cancer. Gamma rays were discovered by French scientist Paul Villard at the start of the 20th century when he was experimenting with radon gas.
Essential Questions for the Electromagnetic Spectrum
What are the uses and dangers of the different parts of the electromagnetic spectrum?
What are electromagnetic waves made of?
How are frequency and wavelength related to danger?
Additional EM Spectrum Lesson Plan Ideas
Have your students make storyboard to show what the world would be like without microwaves.
Get your students make a safety poster for medical professionals working in a hospital. How can they keep themselves safe from some of the harmful EM waves that are used in hospitals?
Have students create their own mnemonic devices for remembering the order to the EM spectrum (or the colors of light) and make a visualization to help them remember it.