electromagnetic spectrumThe whole range of electromagnetic waves, in order. Neighboring bands overlap. Where microwaves end and infrared begins, for one, is a matter of convention.
electromagnetic waveA wave of linked electric and magnetic fields. It needs nothing to travel through, so sunlight crosses empty space.
frequencyHow fast the crests of a wave follow one another. It is counted in waves per second: two waves a second is a frequency of 2 hertz.
gamma rayThe wave type with the shortest waves and most energy. Gamma rays come from radioactive decay, lightning, exploding stars and the regions around black holes.
infraredInvisible light just beyond red, felt as heat. A little over half of the sun's energy arrives at Earth as infrared.
microwaveA short radio wave, a millimeter to a meter long. Microwaves cook food, show rain on weather radar and carry satellite signals through clouds.
radio waveThe wave type with the longest wavelengths of all. Leaving microwaves aside, the shortest are about as long as a football, and the longest are longer than the planet is wide.
Show all 36 terms (29 more)
The seven kinds of wave, continued
speed of lightAbout 300,000 kilometers per second in empty space. That is about 186,000 miles per second, and every electromagnetic wave travels at it in a vacuum.
ultravioletInvisible light with waves shorter than violet's. The kind called UV-B causes sunburn, and ozone in the atmosphere absorbs about 95 percent of it.
visible lightThe narrow band of waves that human eyes can see. It runs from about 380 nanometers to about 700.
wavelengthThe length of one complete wave. It can be measured from one crest to the next. Along the spectrum, energy goes up as the wavelength gets shorter.
X-rayA wave that goes through skin but is stopped by bone. Wilhelm Röntgen discovered X-rays in 1895 and named them X for unknown.
Waves and light 12
electric fieldThe region around a charge where it pushes or pulls. A changing electric field makes a magnetic field, and a changing magnetic field makes an electric one.
hertzOne vibration a second; the measure of frequency. It is named for Heinrich Hertz, who proved in the late 1880s that radio waves exist.
ionizing radiationRadiation strong enough to knock electrons off atoms. X-rays, gamma rays and the more energetic ultraviolet are ionizing. Radio waves, microwaves, infrared and visible light are not.
magnetic fieldThe region around a magnet where its force acts. Moving electric charges make magnetic fields too.
nanometerA millionth of a millimeter. Its symbol is nm. It is a billionth of a meter, and visible light has wavelengths of a few hundred.
photonThe smallest possible bit of light. A photon has no mass and travels at the speed of light.
prismAngled glass that fans a sunbeam out into a rainbow. Each wavelength bends by a different amount as it passes through. Red bends least.
red lightThe visible color with the longest wavelength. It begins at about 625 nanometers and runs to the long end of visible light.
transverse waveA wave that shakes sideways as it moves forward. All electromagnetic waves are transverse. So is a wave flicked along a rope.
vacuumEmptiness: a place holding no air or other matter. Sound cannot cross a vacuum. Electromagnetic waves can.
violet lightThe visible color with the shortest wavelength. Its waves are about 380 to 435 nanometers long. Ultraviolet means beyond violet.
white lightA blend of every color of the rainbow. Isaac Newton concluded that it is a mixture after spreading it into colors with a prism.
Uses and detection 12
antennaA metal device that sends or picks up radio waves. On the way out it changes electric current to radio waves. On the way in it does the reverse.
black lightA lamp that gives off mostly ultraviolet light. Its dim violet glow is the little visible light that gets through its filter.
fluorescenceA glow from a material that has absorbed other light. Many materials glow in colors under ultraviolet, and the glow stops almost at once when the lamp goes off.
ionosphereThe charged upper layer of Earth's atmosphere. Sunlight is what charges it. It bends some radio waves, which helps them reach distant places.
laserA light source whose waves all march in step. Its name was an acronym for light amplification by stimulated emission of radiation. Lasers date from 1960.
microwave ovenA kitchen appliance that cooks with microwaves. Its waves, about 12 centimeters long, make water and fat molecules in the food rotate, and that makes heat.
optical fiberA bendable thread of glass that guides light along. Infrared light loses little strength in the fiber, so signals can go long distances.
ozone layerThe shield of gas in the stratosphere against UV. It was discovered in 1913 and lies some 15 to 35 kilometers above the ground.
radarLocating planes or storms by their radio echoes. The name began as an acronym: radio detection and ranging.
radiographAn X-ray picture of the inside of an object. Dense bone stops more of the X-rays than skin does, so bones show up as shadows on the film.
remote controlA handheld device that operates a machine from afar. Most TV remotes signal with pulses of infrared light from a small LED.
thermal imagingMaking a picture from an object's infrared glow. It lets firefighters see through smoke and find people.
How this list was compiled: Term list chosen for this site on 2026-10-12. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: Electromagnetic spectrum, Electromagnetic radiation, Radio wave, Microwave, Infrared, Light, Visible spectrum, Ultraviolet, X-ray, Gamma ray, Wavelength, Frequency, Speed of light, Hertz, Photon, Nanometre, Vacuum, Transverse wave, Electric field, Magnetic field, Prism (optics), Dispersive prism, Red, Violet (color), Ionizing radiation, Radar, Antenna (radio), Laser, Fluorescence, Blacklight, Ozone layer, Thermography, Radiography, Remote control, Microwave oven, Ionosphere and Optical fiber. Radiograph, black light and white light were also read in Wiktionary, the free dictionary (https://en.wiktionary.org/). The seven kinds of wave, wavelength, frequency, the hertz, the photon, the vacuum, the range of visible light, sunburn and ozone, X-ray pictures, the sources of gamma rays, the remote control and the microwave oven were checked a second time against the Tour of the Electromagnetic Spectrum of NASA Science (https://science.nasa.gov/ems/): Introduction to the Electromagnetic Spectrum, Anatomy of an Electromagnetic Wave, Wave Behaviors, Radio Waves, Microwaves, Infrared Waves, Visible Light, Ultraviolet Waves, X-Rays and Gamma Rays. The fact after each meaning is from the same pages. Licence: own work
How it works
This electromagnetic spectrum vocabulary worksheet prints radio wave, microwave, infrared, visible light, ultraviolet, X-ray, gamma ray and five more terms beside their meanings in another order. The answers are drawn in on a last page.
Read the full guide
Electromagnetic spectrum worksheet: vocabulary for waves and light
Set opens on The seven kinds of wave. Waves and light has hertz, photon, nanometer, vacuum, transverse wave, electric field, magnetic field, prism, white light, red light, violet light and ionizing radiation.
Uses and detection
The third set has radar, antenna, laser, fluorescence, black light, ozone layer, thermal imaging, radiograph, remote control, microwave oven, ionosphere and optical fiber.
Crest, trough, amplitude and the words for reflection and refraction are on the waves word search.
Questions and answers
What are the 7 types of electromagnetic waves in order?
From the longest wavelength to the shortest: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays. Frequency and energy rise in the same order, so gamma rays carry the most energy.
How are wavelength and frequency related?
The shorter the wavelength, the higher the frequency. For an electromagnetic wave in a vacuum, the wavelength multiplied by the frequency always gives the speed of light.
Who discovered the electromagnetic spectrum?
No one person. William Herschel found infrared in 1800 and Johann Ritter found ultraviolet in 1801. In the 1860s James Clerk Maxwell's theory showed how electric and magnetic fields join to make waves, and the other bands followed.