What Travels Through Waves?

Waves are vibrations that transfer energy from one place to another without transferring matter. There are two main types of waves: mechanical waves and electromagnetic waves. Mechanical waves require a medium like air or water to travel through. Examples include sound waves and water waves. Electromagnetic waves consist of oscillating electric and magnetic fields and do not require a medium to propagate. Examples include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

Mechanical waves are created when a source of energy causes a medium to vibrate. The vibrating matter then bumps into neighboring particles, passing on the energy. Electromagnetic waves are created when an electric field couples with a magnetic field. The oscillating electric and magnetic fields then propagate outward from the source. Both types of waves transfer energy from one location to another, but mechanical waves require matter to travel through while electromagnetic waves can travel through empty space.

Electromagnetic Waves

Electromagnetic waves are waves that can travel through a vacuum at the speed of light. They are composed of oscillating electric and magnetic fields that propel the wave forward. Some examples of electromagnetic waves include:

Light Waves

Visible light that we can see with our eyes is part of the electromagnetic spectrum. Light waves have wavelengths between 400-700 nanometers. Different wavelengths correspond to different colors – violet has the shortest wavelengths while red has the longest wavelengths.

Radio Waves

Radio waves have very long wavelengths that range from 1 millimeter to hundreds of kilometers. They are produced by oscillating electric currents and are utilized for radio communication technologies.


Microwaves have wavelengths ranging from 1 millimeter to 1 meter. They are commonly used for radar, navigation systems, microwave ovens, and wireless communications.

Infrared Waves

Infrared waves have wavelengths longer than visible red light but shorter than microwaves. Infrared radiation is emitted by all objects and molecules above absolute zero. It is used for thermal imaging and spectroscopy.

Ultraviolet Waves

Ultraviolet (UV) light has shorter wavelengths than visible violet light. It has germicidal properties and can cause sunburn. The ozone layer absorbs most ultraviolet radiation from the Sun.

X-Rays and Gamma Rays

X-rays and gamma rays have extremely short wavelengths, less than 10 nanometers. They are produced by high energy processes and are very penetrating. X-rays are used medically while gamma rays are emitted by radioactive materials.

Mechanical Waves

Mechanical waves are waves that require a medium in order to transport their energy from one location to another. Unlike electromagnetic waves, mechanical waves cannot travel through the vacuum of outer space. There are three main types of mechanical waves: sound waves, seismic waves, and water waves.

Sound waves are longitudinal waves that travel through mediums like air, water and solids. They can travel distances up to 10-15 km. Sound waves are characterized by their amplitude (loudness), frequency (pitch), and speed. Musical instruments create sound waves that we interpret as music. Our voices also create sound waves that travel from our vocal cords through the air until being received by the ear.

Seismic waves are generated below Earth’s surface by events like earthquakes, volcanic eruptions, explosions, and ocean waves. They travel through the layers of Earth’s interior and are studied by seismologists to determine where earthquakes originate. There are two main types of seismic waves: P waves (primary waves) and S waves (secondary waves). P waves are longitudinal while S waves have a transverse motion.

Water waves travel along the surface of bodies of water like oceans, seas and lakes. Wind, earthquakes, gravity and the Sun’s heat can all generate water waves. Ocean waves come in two main types – surface waves and internal waves. The most common surface waves are ripples, capillary waves, seas and swells. Tsunamis are an example of seismic generated waves.

Light Waves

Visible light waves are the only electromagnetic waves that can be detected by the human eye. Though humans can only see a small portion of the electromagnetic spectrum, that small portion contains all the colors of the rainbow. When white light encounters a prism, the light gets refracted into the colors of the visible light spectrum, from longest wavelength (red) to shortest (violet).

The wavelength and frequency of visible light determines its color. Longer wavelengths with lower frequencies appear red, while shorter wavelengths with higher frequencies appear violet. The entire visible light spectrum ranges in wavelength from 380 to 750 nanometers.

Light travels at different speeds through different mediums. In a vacuum, visible light travels at a constant speed of 186,000 miles per second. This speed is commonly known as the speed of light and represented by the letter c. However, when passing through a material, the speed of light gets reduced as it interacts with the atoms in that material. This reduction in speed is quantified by the refractive index of that material. For example, visible light slows down to 124,000 miles per second in water, which has a refractive index of 1.33.

Radio Waves

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths ranging from 1 millimeter to 100 kilometers. Some common uses and applications of radio waves include:

AM/FM Radio – AM (amplitude modulation) and FM (frequency modulation) radio use radio waves to transmit audio signals and programming. AM radio operates from 535 to 1605 kHz, while FM radio utilizes higher frequencies from 88 to 108 MHz. Radio waves are broadcast from transmitters and received by radio receivers to play audio.

Wireless Networks – Wireless internet networks like WiFi utilize radio waves, typically in bands from 2.4 to 5 GHz. Routers broadcast radio signals that allow internet-enabled devices to connect to the network and access the internet and other devices wirelessly.

Bluetooth – Bluetooth also uses radio waves, usually around 2.4 GHz, for short-range wireless communication between devices like smartphones, speakers, headphones and more. Bluetooth allows data transfer between compatible devices in close proximity.

Remote Controls – Most remote controls use light waves in the infrared spectrum, but some remotes utilize radio waves to communicate with devices without needing line-of-sight. Garage door openers, car keys and some other remotes transmit radio signals to operate doors, alarms, and more from a distance.


Microwaves are a type of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter. Some key uses of microwaves include:

[b]Heating Food:[/b] Microwaves are commonly used for cooking and reheating foods. Microwave ovens work by using microwave radiation to heat up water molecules in food, allowing the food to cook very quickly compared to conventional ovens.

[b]Radar:[/b] Microwaves are used in radar technology, which detects the location and speed of objects like aircraft and weather formations. The short wavelength of microwaves allows radar to accurately detect small objects.

[b]Cell Phones:[/b] Cell phones rely on microwave frequencies to transmit signals and data. Networks like 4G LTE use microwave bands between 700 MHz and 2.6 GHz.

[b]WiFi:[/b] WiFi internet connections also operate on microwave frequencies, typically between the 2.4 GHz and 5 GHz bands. This allows for wireless internet connectivity in homes and businesses.

Overall, microwaves play an important role in communications, radar, and cooking technologies that society relies on today.

Infrared Waves

Infrared waves have longer wavelengths than those of visible light, measuring from about 700 nanometers to 1 millimeter. They are often used for thermal imaging, as objects emit infrared radiation that can be detected by thermal imaging cameras. These cameras are able to create images based on the heat being emitted by objects in the environment. Thermal imaging cameras are useful for a variety of applications such as detecting heat loss in buildings, locating and diagnosing mold, detecting faults in electrical and mechanical equipment, and more.

Infrared radiation is commonly used in heat lamps as well. The infrared waves penetrate the skin and are absorbed, heating up tissues beneath the skin. This helps promote blood circulation and relieve pain and stiffness. Heat lamps using infrared radiation are often found in physical therapy offices or sports medicine clinics.

Infrared astronomy is the branch of astronomy that studies celestial objects in the infrared portion of the electromagnetic spectrum. Observing in infrared allows astronomers to see objects that are too cold to emit much visible light, such as planets, stars, nebulae and galaxies. Infrared observations can also penetrate dusty regions of space which are opaque to visible light. This allows astronomers to see objects and details that would otherwise be obscured.

Ultraviolet Waves

Ultraviolet light, often referred to as UV, has shorter wavelengths than visible light. This special type of radiation has several unique properties and uses.

One of the most common uses of ultraviolet waves is for disinfecting water. When UV light shines through water, it works to kill bacteria and pathogens by disrupting their DNA and preventing replication. This makes UV disinfection a reliable method for ensuring water is free of harmful microorganisms.

Another application of ultraviolet waves is detecting fake money and documents. Many modern currencies have UV reactive features that are invisible under normal light. Shining a blacklight on paper money will reveal hidden watermarks and security threads that counterfeits lack.

UV light is also widely used in forensic analysis. Biological fluids, fingerprints, and other evidence may glow or fluoresce under a blacklight. This allows investigators to easily visualize and photograph these clues at a crime scene.

The most familiar use of UV waves is with blacklight posters and paints. Blacklights emit high concentrations of long wave UV that energize phosphors to create a glow-in-the-dark effect. This explains why certain clothing or teeth whiteners shine brightly under a blacklight.

While ultraviolet radiation has many useful properties, it can also be hazardous. Overexposure to UV from the sun causes skin damage, sunburn, and increases the risk of skin cancer. For this reason, sunscreen and protective clothing are recommended when spending time outdoors in daylight.

X-Rays and Gamma Rays

X-rays and gamma rays are forms of electromagnetic radiation that have very short wavelengths and very high frequencies. They have enough energy to penetrate many materials and are therefore useful for seeing inside objects.

In medicine, X-rays are commonly used for diagnostic imaging and cancer radiation therapy. When X-ray beams pass through the body, denser tissues such as bone absorb more radiation than soft tissues. This allows X-ray images to visualize interior body structures like bones, tumors, and cavities. X-rays can reveal fractured bones, dental issues, pneumonia, breast cancer, and other medical conditions.

Radiation therapy uses targeted X-ray or gamma ray beams to kill cancer cells and shrink tumors. The radiation damages cancer cell DNA, causing them to die. The high-energy beams can be carefully aimed at diseased tissue while minimizing exposure to healthy tissue.

X-rays and gamma rays are also used for scanning cargo, identifying materials, and quality control inspections. Their penetrating ability allows them to scan the interior of objects. Different materials absorb varying amounts of radiation, producing distinct images. This enables the detection of contraband at airports, visualization of manufacturing flaws, and chemical analysis of materials.


This article explored different types of waves and what can travel through them. We learned about electromagnetic waves like radio waves, microwaves, infrared, visible light, ultraviolet rays, x-rays and gamma rays. These waves all transmit energy at different frequencies along the electromagnetic spectrum. We also discussed mechanical waves like sound waves and water waves that require a medium to transport energy.

Understanding the properties of different waves is crucial for harnessing their ability to transmit energy and information. Radio waves made wireless communication technology possible. Light waves enable vision, photography and fiber optic telecommunication. X-rays and gamma rays have important medical and scientific applications. Studying waves reveals insights about the nature of energy and matter that lead to innovations improving our lives.

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