## Shop Windows to the Universe

Ready, Set, SCIENCE!, by the National Research Council, focuses on K-8 science classsrooms. Check out the other publications in our online store, as well as classroom materials.

The wavelength of a wave is the distance from one crest to the next.
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# Wavelength

There are many kinds of waves all around us. Everyone knows about waves of water in the ocean. Did you also know that sound travels through the air in waves? Or that light is actually made up of waves of electromagnetic energy?

The length of a wave is called, well, its "wavelength". If you think about a wave in the ocean, its wavelength is the distance from the top of one wave (called the wave's "crest") to the top of the next wave. You can also measure the distance from the lowest point between two waves (called the wave's "trough") to the next trough. You should get the same distance either way.

The wavelengths of ocean waves we see at the beach are usually 10 or so meters (33 feet) or longer. Sound waves that humans can hear have wavelengths between about 2 cm (an inch) and 17 meters (56 feet). Waves of electromagnetic radiation that we see as light have really, really short wavelengths between 400 and 700 nanometers (a nanometer is one billionth of a meter!).

A wave also has a "frequency". The frequency is how often a crest goes by. The frequency of a wave depends on how fast the wave is moving. It also depends on the wavelength of the wave. Imagine two sets of waves that have the same speed. If one set has a longer wavelength, it will have a lower frequency (more time between waves). If the other set has a shorter wavelength, it will have a higher frequency (less time between waves). Wavelength and frequency go opposite of each other. Shorter wavelengths mean higher frequencies, while longer wavelengths mean lower frequencies.

Sound waves with a wavelength around 34 cm (about a foot) have a frequency of 1,000 hertz. A hertz is one wave per second. So a thousand sound waves can enter your ear in a second! Sound waves travel much faster than normal water waves. Sound waves move through the air at around 343 meters/second (767 miles/hour).

Light moves even faster AND has shorter wavelengths. These combine to give light extremely high frequencies. Red light has a wavelength of about 682 nanometers. Its frequency is around 440 terahertz. That's 440,000,000,000,000 hertz. That's a whole lot of waves going by in a second!

#### Shop Windows to the Universe Science Store!

Our online store includes issues of NESTA's quarterly journal, The Earth Scientist, full of classroom activities on different topics in Earth and space science, as well as books on science education!

## Traveling Nitrogen Classroom Activity Kit

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Electromagnetic radiation is the result of oscillating electric and magnetic fields. The wave of energy generated by such vibrations moves through space at the speed of light. And well it should... for...more

## Electricity and Magnetism

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Radiation comes in two basic types: electromagnetic radiation transmitted by photons, and particle radiation consisting of electrons, protons, alpha particles, and so forth. Electromagnetic radiation,...more

Radio waves are a type of electromagnetic radiation. A radio wave has a much longer wavelength than does visible light. We use radio waves extensively for communications. Radio waves have wavelengths as...more

## Tools for Math and Science

Some ideas are used throughout the sciences. They are "tools" that can help us solve puzzles in different fields of science. These "tools" include units of measurement, mathematical formulas, and graphs....more

## Starting Points for Science

Some ideas are used in many, many places throughout science. We have grouped these "starting points for science" into three clusters: space, time, and matter. "Space" is the word we use for everything...more

## What is a Supercomputer?

Some scientific problems and processes are so complex that you need SUPERCOMPUTING power to tackle them! Just what is a supercomputer? A supercomputer is a computer that is among the largest, fastest or...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information.