Radiation can be defined as the energy that travels through space or through a material medium in the form of particles or waves.
Depending on the energy of the radiated particles, radiations can be categorized into two groups:
Ionizing radiation: carries enough energy (usually more than 10 eV) to ionize molecules, atoms and break chemical bonds. One of the common sources of such radiation is radioactive materials that emit alpha, beta, or gamma radiation.
While ionizing radiation has several beneficial applications, prolonged exposure to it can cause radiation sickness, burns, cancer, and genetic damage.
Non-ionizing radiation: doesn’t carry enough energy per quantum to remove an electron from an atom or molecule. However, it has sufficient energy to move electrons from low to high energy states.
Non-ionizing radiation has a higher wavelength and shorter frequency than ionizing radiation. Typically, it is considered non-harmful, but there could be some risk from extended exposure. For example, it can create non-mutagenic effects such as inciting thermal energy in biological tissue, which could lead to burns.
People often get confused between radiation and radioactivity. Radiation is the movement of energy, whereas radioactivity refers to the splitting or decay of an atomic nucleus. All radioactive materials emit radiation when they decay, but not all radiation types are radioactive. Deuterium (an isotope of hydrogen), for example, isn’t radioactive.
To better explain this concept, we have gathered some of the best examples of radiation that you see in everyday life. The list includes various particle, electromagnetic as well as acoustic radiation.
Table of Contents
14. Heat From Candle
Type: Non-ionizing radiation
Candle uses a chemical reaction to produce light and heat. In this combustion reaction, the wax (typically made of chemicals containing carbon) reacts with the surrounding oxygen to form carbon dioxide and steam.
Heat moves as radiation in space: it travels in straight lines at the speed of light. That’s why people sitting in front of a fireplace feel warm. When they sit too close, only the front is warmed. The backside doesn’t get warmed until they turn around.
13. Infrared Beams Emitted By Remote Controls
Type: Non-ionizing radiation
A remote control unit doesn’t have wires, so it has to transmit signals to whatever it’s operating through electromagnetic waves. Most remote controls do this by using infrared radiation, though some use radio waves to send signals instead.
Early TV remote control (built between the 1950s and 1960s) used ultrasonic waves. Present-day remote controls are consumer infrared devices that transmit infrared radiation in the form of digitally coded pulses to control functions like fan speed, AC temperature, power, volume, channels, or track change.
12. Gravitational Radiation
An Illustration of gravitational waves originating from binary neutron stars | Credit: R. Hurt/Caltech-JP
Type: Non-ionizing radiation
Gravitational waves transmit energy as gravitational radiation, which is a kind of radiant energy similar to electromagnetic radiation. In other words, gravitational radiation is to gravity what light is to electromagnetism.
Theorized by Albert Einstein in 1916, gravitational waves are ripples in the geometry of space and time. Only two fundamental long-range forces exist in nature: gravity and electromagnetism. Just as accelerated electric charges produce electromagnetic radiation, gravitational charges (i.e., masses) produce gravitational radiation.
In 2015, LIGO detected the gravitational waves for the first time (almost 100 years after its prediction). These waves emerged from the merging of a binary black hole system.
11. Laptop Radiation
Type: Non-ionizing radiation
Computers emit several different kinds of radiation, including infrared and low-frequency electromagnetic radiation. Since laptops are kept in direct contact with our laps, their radiation exposure on limited body parts makes it more hazardous.
Laptops’ undersides emit 40 – 100 milliGauss of radiation, which is 40 to 100 times higher than the standard limit of radiation exposure. Furthermore, the older the laptop, the higher the radiation. Prolonged exposure to such radiation could lead to headaches, tiredness, dizziness, sleep disturbances, and memory and concentration disorders.
10. X-rays From an X-ray Machine
Image credit: Authority Dental
Type: Ionizing radiation
An X-radiation is a very high-energy electromagnetic radiation, with frequencies ranging from 30 petahertz to 30 exahertz. It can penetrate body tissue and internal organs.
Today, X-rays are widely used to identify heart diseases, kidney stones, broken bones, and intestinal blockages. They are often used for identifying and destroying cancerous cells.
Basically, an X-ray machine transmits the radiation through the body. Some of it comes out on the other side of the body (where it is exposed to a digital detector to form an image) while some of the radiation is absorbed in body tissues (which is referred to as ‘radiation dose’ a patient gets). Although X-rays are ionizing radiation, their benefits far outweigh potential negative outcomes.
9. Risk Involved In Coal Mining
A coal surface mining site in Bihar, India
Type: Ionizing radiation
Coal is a fossil fuel used to generate power in various countries, including the United States. Since it contains traces of naturally-occurring radioactive substances, workers in coal mines can be exposed to radiation emitted from substances like uranium and thorium.
To monitor and control this radiation exposure, engineers prepare special measurement devices called radiation dosimeters. It tracks the radiation exposure of individual and radiation levels in workplaces like coal mines.
In addition to mining, the process of burning coal also carries the risk of radiation exposure. The coal-fired power plants produce wastes that contain small amounts of radioactive materials. The coal electricity is 10 to 100 times more toxic than electricity generated from natural gas via hydraulic fracturing.
8. Radioactive Elements Used In Nuclear Weapons
10-gram sample of Uranium-238 | Wikimedia
Type: Ionizing radiation
Uranium-238 is the most common, naturally occurring isotope of uranium. Since this isotope has a relative abundance of 99.3% and a half-life of 4.4 billion years, it generates nearly 40% of the radioactive heat produced within the Earth.
Modern nuclear weapons utilize Uranium-238 to increase efficiency and reduce the critical mass (the small amount of fissile material required for sustaining nuclear chain reaction). Castle Bravo, for example, is a thermonuclear weapon that uses Uranium-238 to encase the fusion fuel. This ultimately adds more energy to the ‘yield’ of the weapon.
7. Sound Waves From Speakers
Type: Non-ionizing radiation
Sound waves exist as vibrations of pressure in a medium. They are produced by the vibration of an object, which causes the nearby air particles to vibrate. When these vibrating particles reach the ear, it causes the eardrum to vibrate, which our brain interprets as sound. The quicker the air pressure alters, the higher the frequency of the sound we hear.
When the speaker cones move back and forth, they push on air particles, changing air pressure and ultimately creating soundwaves. However, air particles don’t actually move from the speaker to the ear. Individual particles only travel a small distance as they vibrate, and cause the adjacent particles to vibrate in a rippling effect all the way to your ear.
6. Ultrasound
Type: Non-ionizing radiation
Sound waves with higher frequencies (higher than what humans can hear) are called ultrasound. It is similar to the normal (audible) sound in terms of physical characteristics, except that it has frequencies higher than the upper audible limit of human hearing.
Ultrasound is used in various fields, such as in manufacturing industries for nondestructive testing of structures and products, and in chemical industries for mixing, purifying, or accelerating chemical processes.
Perhaps its most important application is ultrasound imaging, which captures and shows blood flow as well as the movement of the body’s internal organs in real-time. And since sound waves are non-ionizing, they are way safer than X-rays.
5. Cosmic Rays
Type: Ionizing radiation
Comic rays are high energy particles (such as atomic nuclei and protons) that move through space at nearly the speed of light. While many things about cosmic rays remain a mystery, scientists have found evidence that shows they originate from the Sun and distant galaxies.
Cosmic rays often create electronic problems in satellite and other machinery. They ionize the oxygen and nitrogen molecules and create various unstable isotopes in the Earth’s atmosphere, including carbon-14.
Earth’s atmosphere and magnetic field protect the planet from 99.9% of space radiation. However, people outside this shield (astronauts without protection) can receive an immense amount of space radiation, which could increase the risk of fatal cancers.
4. Seismic Waves
Type: Non-ionizing radiation
Seismic waves travel through the layers of Earth. They are caused by magma movement, massive landslides, volcanic eruptions, earthquakes, and artificial explosions that emit low-frequency acoustic energy.
Their propagation velocity relies on the type of wave as well as the elasticity and density of the medium. In water, seismic wavefields are measured by a hydrophone, whereas in air, they are recorded by an accelerometer or seismometer.
3. Lasers
Helium-neon laser at the University of Chemnitz, Germany
Type: Non-ionizing radiation
The word “laser” is an acronym for “light amplification by stimulated emission of radiation.” In this case, the term “light” includes electromagnetic radiation of various frequencies, ranging from infrared and visible light to ultraviolet and even X-rays.
Different types of lasers use different laser medium. Argon, liquid dyes, a mixture of helium and neon, solid crystals, such as ruby, are some of the most common laser media.
Laser radiation is usually not harmful, and it interacts with the body just like ordinary light. However, as per FDA guidelines, laser products must contain the warming of radiation and other hazards.
More Details: What Is A Laser? Acronym | Definition | Working | Types
2. Food Irradiation
Image credit: IAEAvideo/YouTube
Type: Ionizing radiation
Food irradiation is a process of applying ionizing radiation. It enhances and extends the shelf life of food by eliminating or reducing insects and microorganisms. Radiation (such as electron beams, gamma rays, or x-rays) is emitted by radioactive substances or produced electrically.
The process neither makes food radioactive nor noticeably alters its nutritional quality. The appearance, texture, and taste of food remain almost the same. The changes are so minimal that you won’t be able to differentiate between irradiated and non-irradiated food. All sources of radiation (that are used to irradiate food) are regulated by the FDA.
1. Sunlight
Sunlight radiation distribution
Type: Non-ionizing radiation
The rays coming from the Sun is a mixture of electromagnetic waves, in particular, ultraviolet, visible, and infrared light. Studies show that approximately 1.365 kW/m² of solar radiation is received at the top of Earth’s atmosphere.
A significant amount of this radiation (mostly ultraviolet rays) is absorbed by the Earth’s atmosphere, while the rest reaches the ground and heats it up.
The fraction of the ultraviolet radiation that is not absorbed by the atmosphere results in sunburn or suntan on people who have been exposed to sunlight for extended periods.
Sunlight fuels the existence of almost all life on Earth. Autotrophs, like plants, use sunlight along with water and carbon dioxide to produce simple sugar (this process is called photosynthesis). Heterotrophs, like animals, use sunlight indirectly by consuming autotrophs or their products.
Read: 14 Best Examples Of Convection With Simple Explanation
The Sun’s radiation could provide way more energy than what is needed to power the entire world. The Earth’s surface receives 120,00 terawatts of solar radiation, which is 20,000 times more power than what our planet needs.
