Infrared and ultraviolet light are two forms of electromagnetic energy which can be harnessed for different purposes.
Both radiations exist at the two extremes of the electromagnetic spectrum and are invisible to the human eyes.
The electromagnetic spectrum is the range of the frequencies of the various electromagnetic radiations, their respective wavelengths, and photon energies.
The spectrum covers electromagnetic waves with frequencies that range from less than one hertz to over 1025 hertz and corresponding to wavelengths from thousands of kilometers to a fraction of infinitesimal size.
Prior to the 1860s, electricity, and magnetism were believed to be separate forces. However, in 1873, James Maxwell observed that:
- An electric current in a wire produces a magnetic field whose direction depends on the direction of the current.
- A moving electric field produces a magnetic field and vice versa
- Magnetic poles come in pairs that attract and repel each other, much as electric charges do.
These discoveries led to the development of a unified theory for electricity and magnetism, giving birth to electromagnetism. This deals with how electrically charged particles interact with one another and with the magnetic field.
Electromagnetic radiation is created when an electric field accelerates an electron to move.
The movement produces oscillating electric and magnetic fields which travel in a bundle of light energy called a photon.
Infrared and Ultraviolet radiations share striking similarities. For instance:
- They are both invisible to the human eyes and transmitted as waves consisting of changing magnetic and electric fields.
- The waves are self-propagating and carry a bundle of energies which are converted to heat.
Despite these basic similarities, there are also some important differences and this is exactly what I am going to point out in the next section.
Infrared vs UV Radiation
To make this easier, we are going to consider these differences in 4 important areas:
- The danger factor
- The heating effect and
- Main uses
So let’s get started.
Before we dive in fully, it is important we establish first what frequency is. So, electromagnetic radiation is transmitted in the form of waves.
A simple wave is composed of two parts, the wave crest which is the upper part of the wave and the trough, which is the lower part.
These two parts make a complete wave cycle.
So in a nutshell, an electromagnetic frequency is the number of wave cycles that are made in a unit time, especially in a second and it is measured in Hertz (Hz).
Infrared and Ultraviolet radiation have different frequencies.
It has a frequency that roughly covers the range 300 GHz to 400 THz and has a wavelength of 1mm – 750 nm.
This wavelength refers to the distance between two successive wave crests and it determines the energy band and lattice vibration of the EM radiations.
Infrared radiation can be generally divided into three parts.
- Far-infrared covers the range 300 GHz to 30 THz and has a wavelength of 1 mm – 10 µm
- Mid-infrared covers the range from 30 THz to 120 THz with a wavelength of 10 µm – 2.5 µm
- Near-infrared covers the range 120 THz to 400 THz with a wavelength of 2.5 µm – 750 nm.
Ultraviolet radiation can be found naturally in the sun rays and it constitutes about 10% of the total light output of the sun.
It has a frequency that falls in the range of about 8 x 1014 Hz to 3 x 1016 Hz and has a wavelength of about 380 nm to 10 nm and just like infra-red radiations; it is also divided into 3 bands.
- UVA or near UV has a wavelength in the range 315 – 400 nm
- UVB or middle UV has a wavelength of 280 – 315 nm and finally
- UVC or far UV which has a wavelength of 180 – 280 nm.
The Danger factor
The notion of radiation conjures a frightening imagination, but it is important to point out that not every radiation is bad.
In fact, the use of infrared radiation in a non-invasive healing procedure has been proven to be scientifically safe.
Again, everything the human eyes can see basically radiates infra-red continuously and this can only mean that infra-red is not dangerous.
However, exposure for too long can damage the eyes. This is the reason people that work in industries that expose them to infrared radiation for too long wear goggles.
Again, large doses of this radiation can damage the skin and tissues and it is also responsible for the greenhouse effect.
This causes an increase in temperature and changes in weather patterns and this poses a serious danger to both humans and animals.
Unlike infrared radiation, exposure to the UV radiation is harmful to the skin from the word “go” because of its higher energy.
It has been proven to be the primary cause of skin cancer.
This happens when the skin is exposed to UV radiation. This exposure causes the melanin which acts as the body’s natural defense against this radiation to kick in, so as to absorb the Ultraviolet light and dissipates it as heat.
But when these defenses are overwhelmed as a result of continuous exposure, it will lead to a toxic reaction that will result in a skin burn.
This is likely to happen within half a day of over-indulging in the sun.
In the long-term, ultraviolet radiation can damage the DNA in the body’s cell. This can lead to a mutation that can result to skin cancer and according to the Skin Cancer Foundation, the risk for Melanoma, the deadliest form of skin cancer is twice for people who have suffered skin burn for five or more times.
Fortunately for dark-skinned people, this risk is lower than for light-skinned people.
Finally, like the infrared radiation, the Ultraviolet rays can also damage the eyes. This is because the human eyes are sensitive to all EM radiations.
Like we pointed out earlier, both are propagated as waves which are then converted to heat.
However, the degree of their heating effects differs to a considerable extent.
For instance, infrared radiation heats an object such that there is an even spread of warmth across that object and unlike conventional heats, infrared does not heat air.
We can feel the heat from infra-red and it can also be used to prepare foods. But in the case of Ultraviolet radiations, we can’t directly feel the heat even though it is more energetic than infra-red.
Now, it is important to point out that the heat we feel from sunlight is infrared radiation. This might be surprised when we consider the facts that:
- The sunlight is the primary natural source of ultraviolet radiation.
- And, the proportion of UV light from the sun is more than that from infrared.
So we can safely assume that infrared is hotter than UV radiation because we can feel it as heat while we can’t directly feel UV radiation. It gets into our body and breakdown molecules without generating much heat.
Both have found wide applications in modern medicine.
Though the prolonged exposure of the skin to the UV light can result in skin cancer, the same UV light has found applications in the cure of cancerous growths.
I guess this an interesting irony.
Apart from treatments of cancers, UV light can also be used to treat eczema. It is used in hospitals to sterilize surgical equipment and the air in operating theaters.
UV light equally has wide application outside the medical field.
For instance, it is used in drying or curing inks or coatings. It provides an effective way to treat water and it is also used in fluorescence tubes to provide lighting.
The police use UV light in forensic investigations to detect finger and shoe prints.
In medicine, infra-red has been successfully used in the diagnosis of breast cancer, diabetes neuropathy and detection of other medical issues. It is used in some clinics to relieve pains and heal wounds in non-invasive procedures.
The radiation has been used in night vision technology to amplify light in dark situations to enable imaging or video recording. It is also used in thermography to determine the temperature of objects and it is can detect objects that are too cold to emit visible light.
It is used in aerial defense by the military to track incoming missiles and it has also found a useful application in heat generation.
Now, what next?
Before we wrap up this article, here are a few interesting facts about UV and infrared radiations:
- Every known object in the world including ice cubes radiates infra-red heat.
- Fishes use it to capture preys and for swimming orientations
- The Ultraviolet light is invisible to human eyes but bees can see Ultraviolet light.
- Dragonflies use Ultraviolet vision to see water at a great distance.
Wrapping it up
Infrared and Ultraviolet radiation are two parts of the electromagnetic spectrum. Despite striking similarities between the two, there are other notable differences.
Both radiations have found application in a wide range of areas cutting across medicine, industrial uses, and daily home usage.