The ultraviolet spectrum can be divided into three regions based on wavelength: UV-A \((315-400 \mathrm{nm}), \mathrm{UV}-\mathrm{B}(280-315\) \(\mathrm{nm} ),\) and \(\mathrm{UV}-\mathrm{C}(100-280 \mathrm{nm}) .\) (a) Photons from which region have the highest energy and therefore are the most harmful to living tissue? ( b) In the absence of ozone, which of these three regions, if any, are absorbed by the atmosphere? (c) When appropriate concentrations of ozone are present in the stratosphere, is all of the UV light absorbed before reaching the Earth's surface? If not, which region or regions are not filtered out?

Understanding the energy of photons within the ultraviolet spectrum is pivotal for a range of scientific applications, from studying environmental impacts to designing protective materials. The energy of a photon is inversely proportional to its wavelength, following the formula \( E = h \frac{c}{\lambda} \), where \( E \) is the energy, \( h \) is Planck's constant, \( c \) is the speed of light, and \( \lambda \) represents the photon's wavelength.

For UV-A (\( 315-400 \, \text{nm} \)), UV-B (\( 280-315 \, \text{nm} \) ), and UV-C (\( 100-280 \, \text{nm} \)), one can determine that UV-C photons have the highest energy due to their shortest wavelengths. It's this higher energy that contributes to the potential harm UV-C can inflict on living tissues, making it the most dangerous among the UV spectrum.

The ultraviolet radiation that reaches the Earth has profound effects on both the environment and living organisms. UV radiation can lead to skin damage, including sunburn, premature aging, and an increased risk of skin cancer in humans. Additionally, it can also affect other living organisms, disrupting growth and reproductive patterns.

UV radiation's impact extends to materials like plastics and paints, causing them to degrade over time. Therefore, it is crucial for scientific and medical research to understand the penetrative abilities of different UV regions to protect against these detrimental effects effectively.

The ozone layer serves as a protective shield, absorbing a significant portion of the UV radiation, particularly in the UV-C and UV-B regions. The absorption of UV-C is nearly complete, thanks to the ozone molecules, which strongly absorb photons in this region, preventing them from reaching the Earth's surface.

In the absence of the ozone layer, Earth would be exposed to much higher levels of harmful UV radiation. Surprisingly, a part of UV-B does make it through the ozone layer, although in a considerably attenuated form. UV-A is absorbed the least and thus represents the majority of UV radiation that reaches the ground, leading to the relatively higher safety measures needed against this particular range during outdoor activities.