UVA/UVB Light: Why does UVA penetrate deeper into the skin?

In summary, the difference in wavelength between UVA and UVB radiation does not solely determine their penetration depth in the skin. Other factors, such as the energy and intensity of the waves, also play a role. UVA radiation has a longer wavelength but a lower energy and intensity compared to UVB, allowing it to penetrate deeper into the skin. However, this does not mean that UVA is more harmful than UVB, as both types of radiation can cause damage to the skin.
  • #1
finnch
4
0
[Mentor's Note: Thread moved from New Member Introductions]

Hello,

My name is Chris and I am trying to understand why UVA radiation, with a longer wavelength, penetrates deeper into the skin than UVB which has a shorter wavelength.

Since E=hv=hc/ λ and
c44eb3c2af933606f2bb928132d7ec21.png


then how does a lower energy and lower intensity UVA wave penetrate deeper into the skin than a UVB wave?

Pardoning the pun, I would appreciate it if someone could enlighten me :eek:)

Many thanks...
 
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  • #2
Hi finnch. :welcome:

Yours is a good question, though you won't get an answer to it in this part of Physics Forums. :oldfrown:

To understand why, please refer to the response I wrote in an earlier thread here: https://www.physicsforums.com/threads/pipe-diameter-increase.819442/#post-5143656
 

1. What is the difference between UVA and UVB light?

UVA and UVB light are both forms of ultraviolet radiation emitted by the sun. The main difference between them is their wavelength - UVA has a longer wavelength than UVB. This means that UVA penetrates deeper into the skin, while UVB is mostly absorbed by the outer layers of the skin.

2. Why does UVA penetrate deeper into the skin?

The longer wavelength of UVA light allows it to penetrate deeper into the skin. This is because longer wavelengths have lower energy levels and are less likely to be absorbed by molecules in the atmosphere or skin. As a result, UVA can reach the deeper layers of the skin, where it can cause damage to cells and DNA.

3. How does UVA light affect the skin?

UVA light can cause skin damage in several ways. It can penetrate deep into the skin and cause premature aging, wrinkles, and age spots. UVA can also damage the DNA in skin cells, leading to an increased risk of skin cancer. Additionally, UVA can suppress the immune system, making the skin more vulnerable to infection and disease.

4. Can UVA light be blocked or filtered out?

UVA light can be partially blocked or filtered out by certain substances, such as sunscreen or clothing. However, it is difficult to completely block UVA without also blocking UVB, which is necessary for vitamin D production. Therefore, it is important to use broad-spectrum sunscreen that protects against both UVA and UVB rays.

5. How can I protect my skin from the harmful effects of UVA light?

To protect your skin from UVA light, it is important to limit your exposure to the sun, especially during peak hours when the sun's rays are strongest. Wearing protective clothing, such as hats and sunglasses, can also help. Applying broad-spectrum sunscreen with a high SPF can provide additional protection from UVA light. It is also important to regularly check your skin for any changes or abnormalities and consult a doctor if you notice anything concerning.

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