Ultraviolet radiation

Definition

Ultraviolet radiation (UV) is a form of electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays, ranging from about 10 nm to 400 nm. UV radiation is divided into three categories: UVA, UVB, and UVC, each with differing effects and energy levels.

5 Must Know Facts For Your Next Test

1. Ultraviolet radiation has higher photon energies compared to visible light due to its shorter wavelengths.
2. UV photons can cause ionization in atoms and molecules, leading to chemical reactions such as the formation of ozone in the Earth's stratosphere.
3. The photoelectric effect, important for understanding quantum physics, involves UV light ejecting electrons from metal surfaces.
4. Humans are exposed to UV radiation primarily through sunlight; however, most of the harmful UVC rays are absorbed by the Earth's atmosphere.
5. UVA has the longest wavelengths (320-400 nm), followed by UVB (280-320 nm), and UVC (100-280 nm), with UVC being the most energetic and potentially harmful.

Review Questions

• What is the wavelength range of ultraviolet radiation?
• How does ultraviolet radiation contribute to the photoelectric effect?
• Which type of UV radiation is mostly absorbed by the Earth's atmosphere?

Related terms

Photon: A quantum of electromagnetic energy that exhibits both particle-like and wave-like properties.

Electromagnetic Spectrum: The entire range of electromagnetic waves, from radio waves to gamma rays, including visible light.

Photoelectric Effect:

\text{The phenomenon where electrons are ejected from a material's surface when it absorbs photons with sufficient energy.}