What Are the Types and Uses of Ultraviolet Radiation?
Ultraviolet radiation lies on the electromagnetic spectrum that extends from the violet (short-wavelength), i.e., the end of the visible light range to the X-ray region. Ultraviolet (UV) radiation is imperceivable by our eyes, although, when it falls on certain materials, it may cause them to fluoresce a.k.a emit electromagnetic radiation of lower energy, such as visible light. Many insects like bees can see ultraviolet radiation.
In this article, we will learn about UV rays (UV radiation), the range of ultraviolet, and Ultraviolet light uses.
Ultraviolet Spectrum
The Range of Ultraviolet radiation is between 400 nanometres (1-nanometre or 10−9 meter) on the visible-light spectrum and about 10 nm on the X-ray side.
Although some authorities have extended the short-wavelength limit to 4 nm; however, in physics, ultraviolet radiation is divided into the following four regions:
Near - 400 to 300 nm
Middle - 300 to 200 nm,
Far 200 to 100 nm, and
Extreme, i.e., below 100 nm).
Types of UV Rays
[Image will be uploaded soon]
Ultraviolet light is also known as UV light is one of the types of electromagnetic radiation that emits from the sun and gets transmitted at varying wavelengths and frequencies. On the electromagnetic spectrum, UV light falls between visible light and X-rays (as we discussed above) and it can be divided into UVA or near UV, UVB or middle UV, and UVC or far UV.
Based on the interpretation of wavelengths of ultraviolet radiation with biological materials, three types of UV rays are as follows:
UVA Rays - Wavelength ranges from 400 to 315 nm. UVA is also called blacklight.
UVB Rays - Wavelength ranges from 315 to 280 nm. UVB Rays are well-known for the hazardous effects of radiation on organisms.
Ultraviolet C Light - Wavelength ranges from 280 to 100 nm. The UV rays do not reach Earth’s surface. However, they are very harmful and cause skin cancer and many health issues.
UV Radiation
UV radiation is created by very hot surfaces, like the Sun, in a continuous spectrum.
Ultraviolet waves are produced by atomic excitation in a gaseous discharge tube as a discrete spectrum of wavelengths.
Most of the UV radiation in sunlight gets absorbed by oxygen in Earth’s atmosphere that forms the ozone layer at the lower stratosphere. Out of the 99% Ultraviolet rays that do reach Earth’s surface, almost 99 percent are UVA rays.
UVB Rays
When the ozone layer becomes thin or the ozone layer depletion occurs, more UVB radiation reaches Earth’s surface and causes harmful effects on organisms.
For instance, many studies have shown that UVB radiation crosses the oceanic surface and is lethal to marine plankton to a depth of 30 meters, i.e., around 100 feet in clear water.
Do You Know?
Marine scientists discovered that a rise in UVB rays levels in the Southern Ocean from the year 1970 to 2003 was strongly associated with a continuous decline in fish, krill, and other marine life.
Now, let’s discuss the Ultraviolet Uses:
Uses of UV Rays
Ultraviolet light uses range from medical therapy to photography. Now, let’s discuss some uses of Ultraviolet rays in detail:
Tanning
While walking on hot days, our skin gets exposed to UVB rays, the body’s innate defense system kicks in, and therefore, generates a pigment known as melanin. This melanin absorbs UV light and spreads it as heat. Your skin gets darker because the body sends a signal as melanin into the surrounding cells to prevent skin damage. However, tanning booths use artificial UV light in lamps that pass electric currents via a gas such as a vaporized mercury.
Lamps
Many natural and recreational substances can absorb UV radiation, like plants, fungi, and synthetic fluorophores. When the UV rays are absorbed, the electrons in the material reach a higher energy state, and before reaching their power level gradually in a step-by-step fashion release some of their absorbed energy as visible light.
Fluorescent lamps ionize vapor in their tubes, thus electrons in the gas emit photons at the Ultraviolet spectrum frequencies.
For example, a phosphor layer on the inner core of the tube changes the UV rays to a standard visible light.
Chemistry
Many scientists use UV rays to analyze and study the chemical composition and structure of compounds through color variations. A mechanism called spectroscopy employs a device, viz: spectrophotometer that is much more sensitive to color than our eyes.
A beam of Ultraviolet light is passed through a solution and a spectrometer shows how much UV light is absorbed by a compound using color changes.
The same method is applied to chemicals, biological plants. Hospitals, water quality control labs, petrochemical, and food industries.
For instance, it can display unwanted compounds residing in water by monitoring the color of water during the drinking water production process.
Photography
UV photography is used in medical, scientific fields, and forensic labs. It uses certain lenses to let UV rays pass via the lenses of a camera.
Nature photographers use UV photography to capture patterns in flowers that are unperceivable to our eyes. By modifying their camera, they can gather the UV light that strikes the camera sensor.
FAQs on Ultraviolet Radiation: Comprehensive Guide for Students
1. What is ultraviolet (UV) radiation in the context of the electromagnetic spectrum?
Ultraviolet (UV) radiation is a form of electromagnetic energy that is invisible to the human eye. It is located on the electromagnetic spectrum between visible light and X-rays. Its wavelength ranges from approximately 10 nanometres (nm) to 400 nm, making it shorter than visible light but longer than X-rays. The primary natural source of UV radiation is the Sun.
2. What are the different types of UV radiation and which are most harmful to humans?
UV radiation is primarily categorised into three types based on wavelength:
- UVA (315-400 nm): This is the longest wavelength UV radiation. It penetrates deep into the skin and is responsible for premature skin ageing and wrinkling. Most of it reaches the Earth's surface.
- UVB (280-315 nm): This type has a medium wavelength. It is mostly absorbed by the Earth's ozone layer but is the primary cause of sunburn and is strongly linked to the development of skin cancer.
- UVC (100-280 nm): This is the shortest wavelength and most energetic type of UV radiation. While it is the most damaging, it is completely absorbed by the ozone layer and atmosphere, so it does not naturally reach the Earth's surface.
Therefore, while UVC is intrinsically the most dangerous, UVB radiation poses the most significant health risk from sun exposure.
3. What are some of the most important beneficial applications of ultraviolet radiation?
Despite its risks, ultraviolet radiation has several important uses in science, industry, and medicine. Key applications include:
- Vitamin D Synthesis: Exposure to UVB rays triggers the production of Vitamin D in human skin, which is essential for bone health.
- Sterilisation and Disinfection: UVC light is a powerful germicide used to sterilise medical equipment, purify water, and clean air, as it destroys the DNA of bacteria and viruses.
- Medical Treatments: Controlled doses of UV light are used in phototherapy to treat skin conditions like psoriasis, vitiligo, and eczema.
- Fluorescent Lamps: UV radiation interacts with a phosphor coating inside fluorescent bulbs, causing the coating to emit visible light efficiently.
- Forensics and Authentication: UV light is used to detect counterfeit currency, analyse crime scenes for bodily fluids, and authenticate documents.
4. How does overexposure to UV radiation negatively affect human health?
Excessive exposure to UV radiation, particularly from the sun, can cause significant damage to human health. The primary negative effects include DNA damage in skin cells, which can lead to various health issues such as sunburn, premature skin ageing (wrinkles and sunspots), and an increased risk of developing skin cancers like melanoma. It can also harm the eyes, leading to conditions like cataracts and photokeratitis (sunburn of the cornea).
5. Why is the Earth's ozone layer so crucial for protecting us from UV radiation?
The ozone layer, a region in the Earth's stratosphere, acts as a natural shield against the most harmful forms of solar UV radiation. It is highly effective at absorbing approximately 97-99% of the Sun's medium-to-high frequency ultraviolet light. It completely blocks the most dangerous UVC rays and absorbs most of the UVB rays. Without this protective layer, these high-energy rays would reach the surface, causing severe damage to the DNA of all living organisms and making life on Earth as we know it impossible.
6. How does ultraviolet (UV) radiation differ from infrared (IR) radiation in its properties and effects?
UV and IR radiation are both parts of the electromagnetic spectrum but differ significantly. UV radiation has a shorter wavelength and higher energy than IR radiation. Because of its higher energy, UV radiation causes photochemical effects, meaning it can trigger chemical reactions, damage DNA, and cause materials to fluoresce. In contrast, IR radiation's lower energy primarily causes a thermal effect, which we perceive as heat, by making molecules vibrate. Their applications also differ: UV is used for sterilisation, while IR is used for heating and in remote controls.
7. How exactly does UV light work to sterilise water or medical instruments?
The sterilisation process using UV light is a physical, not chemical, method known as Ultraviolet Germicidal Irradiation (UVGI). It uses short-wavelength UVC light, typically around 254 nm. At this wavelength, the UV energy is strongly absorbed by the DNA and RNA of microorganisms like bacteria and viruses. This absorption of energy creates thymine dimers, which damage the genetic material and disrupt its ability to replicate. By preventing the microbes from reproducing, they are rendered non-infectious and effectively killed.
8. What are some common man-made sources of ultraviolet radiation?
While the Sun is the main natural source, several artificial sources of UV radiation are common in daily life and industry. These include:
- Tanning Beds: These use lamps that emit UVA and UVB rays to induce a tan.
- Black Lights: These lamps emit long-wave UVA radiation, causing fluorescent materials to glow.
- Welding Arcs: The high-temperature arc produced during welding generates intense UV radiation across the full spectrum.
- Mercury-Vapour Lamps: These are used for street lighting and in industrial settings and emit UV radiation along with visible light.
- Germicidal Lamps: These are specifically designed to produce UVC radiation for sterilisation purposes in hospitals and water treatment facilities.
