Pre-lab PowerPoint Lesson for S.W.A.T. E-lab

It all starts with vibrations! Vibrations are waves of energy that move from one place to another. These vibrations can occur in…. Water – waves on the ocean shore Electricity – running through a wire Light – from the Sun or light bulbs Air – vibrating string in a piano

Electromagnetic Spectrum Whenever you watch TV, send a text message, or heat food in a microwave, you are using waves. Some waves, like sound waves, need molecules to travel through. This is why you can hear sound in our atmosphere but not in space. Some waves, however, do not need molecules to travel. These waves are called electromagnetic waves. These waves can travel through solid materials - but they can also travel through empty space.

Electromagnetic Waves The word electromagnetic comes from the two words ‘electricity’ and ‘magnetism’. When an electric field and magnetic field move together, they make waves - electromagnetic waves!

Parts of Waves Waves go up and down, and they move forward - like a shaken rope. (How Long) (How Tall)

Wavelength The length of a wave from crest to crest is called WAVELENGTH. The different waves of the spectrum can be as small as the nucleus of an atom, or as big as a planet! (How Long) (How Tall)

Frequency How many waves move pass a point in one second is called FREQUENCY. The more wiggles the higher the energy. Different colors of light are due to waves of different length and frequency

The height of a wave is referred to as AMPLITUDE. (How Long) (How Tall) With sound waves, the higher the amplitude, the louder the noise.

Types of Waves There are many types of waves along the electromagnetic spectrum, from very long radio waves to very short gamma rays. We are only able to see a small portion of this spectrum called visible light. However, scientific instruments use the full range of the electromagnetic spectrum to study and learn about both Earth and space.

Radio Waves Radio waves have the longest wavelengths in the electromagnetic spectrum. They can be as large as a football field to larger than our planet! They have the lowest frequency of all the electromagnetic waves. Since radio waves can carry energy, we use them to transmit information by changing either the frequency or the amplitude of the radio wave to encode a message. Radio waves are useful because they can travel through many different materials, like clouds, without being absorbed. Radio telescopes are used to view planets, comets, giant clouds of gas and dust, stars, and galaxies.

Microwaves Microwaves are higher frequency than radio waves. They range in size from about 1 millimeter to 1 foot long. You are probably most familiar with them when you heat your food up in a microwave, but they have a lot more uses including weather forecasting and cell phones! Microwaves can even pass through clouds, which make them an excellent wavelength for transmitting satellite communications. In 1965, two scientists at Bell Labs, Arno Penzias and Robert Wilson, detected a strange background noise. The scientists soon realized that they had discovered noise left over from the Big Bang that began the universe billions of years ago!

Infrared Infrared waves are about the length of a grain of sand. While we cannot see infrared, we can sense some of the energy as heat. Infrared light is used in television remote controls and even in video games. We can use infrared cameras to study heat loss patterns, such as from a house. This can help us to better insulate openings such as doors and windows to keep thermal energy in and reduce the cost to heat the house. Infrared energy can reveal objects in the universe that cannot be seen in visible light using optical telescopes. Infrared light is helpful in studying new stars because often dense gas clouds block their visible light.

Visible Light All electromagnetic radiation is light, but we can only see a small portion of this radiation. This is the part of the spectrum we call visible light. Each color of the visible light spectrum has a different wavelength. This is why when white light travels through a prism, the wavelengths separate into the colors of the rainbow. Your color TV has only red, green and blue dots but these make all the other colors on your screen. Objects appear to be different colors because they absorb different amounts of the red, green and blue light. They reflect the rest of the wavelengths in visible light and this is the color we see.

Radiation from Sun About 43% of the total radiant energy from the sun is in the visible parts of the spectrum. Most of the remainder is in the near-infrared (49%) and ultraviolet section (7%). Less than 1% of solar radiation is emitted as x-rays, gamma waves, and radio waves.

Ultraviolet Ultraviolet (UV) light has shorter wavelengths than visible light. Although UV waves are invisible to the human eye, some animals can see them. The Sun is a source of the full spectrum of ultraviolet radiation, UV-A, UV-B, and UV-C waves. UV-C rays are the most harmful but are almost completely absorbed by our atmosphere. UV-B rays are the harmful rays that can cause our skin to burn. About 95 percent of UV-B rays are absorbed by ozone in the Earth's atmosphere. Young stars shine most of their light in the ultraviolet wavelength, so scientists are able to study the formation of new stars using ultraviolet telescopes.

X-Rays X-rays have much higher energy and much shorter wavelengths than ultraviolet light. X-rays were first studied in 1895 by a German scientist named Wilhelm Conrad Roentgen. He discovered that aiming x-rays through the human body created detailed images of the bones inside. Because bones are so dense, they absorb more x-rays than skin does creating shadows on the x-ray film. Some things in space naturally emit x-rays. The hotter the object is, the shorter the wavelengths that are emitted. Earth's atmosphere blocks x-ray radiation. This is beneficial for us here on Earth, because x-rays are so energetic that they would harm almost every living thing on earth!

Gamma Rays Gamma rays have the smallest wavelengths and the most energy of all the waves. They are produced by the hottest and most energetic objects in the universe. On Earth, gamma waves are created by nuclear explosions, lightning, and radioactive decay. Exposure to these high-energy waves can cause damage to cells in living things. Sometimes, though, these changes to cells can be helpful. Gamma radiation is used to kill cancer cells. Gamma-ray bursts are the most energetic and luminous electromagnetic events and can release more energy in 10 seconds than our Sun will emit in its entire 10-billion-year expected lifetime! Scientists can also use gamma rays to determine the elements on other planets.

Dangers of the Spectrum Some waves can be harmful if you are exposed to them for too long. The side of the spectrum with wavelengths shorter than visible light tend to be more dangerous to humans because they can have effects on the cellular level. The Sun bombards our Earth constantly with electromagnetic energy. However, the Earth's atmosphere protects us from higher energy waves that can be harmful to life. Some waves, such as visible light and microwaves, pass through the atmosphere. While the atmosphere is essential to protecting life on Earth, it is not helpful when it comes to studying waves in space. Because it blocks much of the radiation, instruments have to be positioned above the atmosphere in order to study higher energy and even some lower energy sources.

Now let’s see you create your own electromagnetic spectrum in the Spectrum Scramble Activity!