Ultraviolet radiation (UV)

Definition

Ultraviolet radiation (UV) is a form of electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays. It is divided into three categories: UVA, UVB, and UVC.

5 Must Know Facts For Your Next Test

1. UV radiation has wavelengths ranging from about 10 nm to 400 nm.
2. UVA (320-400 nm) penetrates the skin more deeply and contributes to skin aging.
3. UVB (280-320 nm) is responsible for causing sunburn and has a higher energy level than UVA.
4. UVC (100-280 nm) is the most dangerous type but is mostly absorbed by the Earth's atmosphere and does not reach the surface.
5. The energy of UV radiation can be calculated using Planck's equation: $E = h \nu$, where $h$ is Planck's constant and $\nu$ is the frequency.

Review Questions

• What are the wavelength ranges for UVA, UVB, and UVC?
• How does UV radiation affect human skin differently in terms of UVA and UVB?
• Why doesn't UVC reach the Earth’s surface?

Related terms

Electromagnetic Spectrum: The range of all types of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Planck's Constant: $6.626 \times 10^{-34}$ Js, a fundamental constant used to describe the sizes of quanta in quantum mechanics.

Photon: A particle representing a quantum of light or other electromagnetic radiation, which carries energy proportional to its frequency.