What is UVA and UVB Light ?

Many people may be interested in finding answers for the following questions:

• What is UVA  ?
• What is UVB ?
• What is UVC ?
• What is UVA and UVB and UVC Light ?

UV is a short abbreviation of ultraviolet, it usually refers to wavelength of light from 10nm to 400nm, which is invisible to human eyes,  there are three types of spectrums that resides in that broad wave region, UVA UVB UVC are the wavelength between 100nm and 400nm.

Based on the physics formular we’ve learn

E=hV(E represent Energy, h stands for a constant number, V represents frequency of the light atom)

λ=υT=υ/f ( λ represent wavelength, υ stands for light speed, it is a constant number, T stands for time, f represent frequency)

Therefore, we know the higher the frequency is, the larger the energy is.

Final result is clear, the short wave UV or UVC has the highest energy and cause more damage than other UV.

According to the WHO, UVA refer to light beam 315-400 nm, which is known as long-wave UV, soft UV or UV blacklight (black light, invisible to human eyes, but some animals visual range can be extended to UVA), and cannot be absorbed by the Ozone Layer.

UVA accounts for 95% of UV radiation from the sun reaching the earth’s surface. As the UVA is long wave and can penetrate deep layer of skin,.

Gernerally, if you put yourself in the hot sunshine ray for a moderate time, your skin would not burn, as sunburn is caused by UVB light.

However, excessive UVA radiation exposure would expedite the skin cells aging, called as intermediate tanning effect, overtime, it would cause wrinkle easily, therefore you might need the sunscreen lotion to help overcome that.

However, we should avoid to work too long under hot sunlight though the consequence is not long-lasting damage,  and studies shows it  is not a related cause of skin cancer.

The application of UVA is that we can use it to detect the crack of  pottery or china or glass, liquid (oil) leakage that is unnoticeable to the eyes or use it to display  the radioactive material like fluorescing painting, glowing toy and poster or counterfeit mony detection.

UVB refer to the light 280-315 nm, which is known as medium-wave UV or intermediate UV, mostly can be absorbed by Ozone Layer and filtered by the atmosphere.

Wavelengths in this spectrum contribute greatest to the biosynthesis of vitamin D in animals.

Since  intermediate wavelength lead to medium penetration capability, it can only reach the skin surface,  therefore, it would cause delayed tanning and burning on the superficial skin, it is proved to be a main cause of skin cancer if a man has too much shine of it.

UVC refers to light 100-280 nm, which is known as short wave UV or germicidal UV, it is a kind of ionizing radiation and harmful to human body or animals, even micro organism like bacteria and virus. Luckily, it can be fully absorbed by Ozone Layer and atmosphere and cannot reach the earth’s surface.

The application of UVC light is widely used for disinfection and sterilization in health and medical industry, over the passed 3 years in our fight against COV-19 pandemic, we use it to kill the virus on our personal wears and equipments.

In the long run, LED UVC lamps would still be an efficient way to kill the pathogenic microorganisms.

If a light can give off  one of the three UV light bands, UVA, UVB or UVC, we can call it UV lamp.

The difference between them is that which UV band the light emits.

According to the light source development history, incandescent lamps and halogen lamps , fluorescent lamps, Mercury-vapor lamps and LED are artificial sources for UV light.  People would use coating or different phosphor to filter or absorb the unwanted spectral line and get the right UV.

Below are some cheap ways to get the UVA UVB UVC light.

Incandescent lamp with a filter coating  – emit UVA light

Halogen lamp with fused quartz envelopes – emit UVA light

Fluorescent lamp with phosphor on the inner tube – emit UVA light

Mercury-vapor lamp  with UV-emitting phosphor  – emit UVA light

Fluorescent lamp with no phosphor coating but fused quartz – emit UVC light

LED – emit UVA UVC light