Contents
Key Stage 4
Meaning
Ultra-violet is the third highest frequency and third shortest wavelength electromagnetic waves.
About Ultra-violet
- Ultra-violet is a transverse waves.
- Ultra-violet can travel through a vacuum as well as through gases in the Earth's atmosphere.
- The speed of ultra-violet through a vacuum is 300,000,000m/s.
As a wave ultra-violets can be:
- Transmitted - ultra-violets can pass through a medium.
- Absorbed - The energy transferred by ultra-violet can be taken in by certain materials, particularly dark coloured materials.
- Reflected - Ultra-violet can bounce off an interface between two media, particularly the surface of a shiny metal.
- Refracted - Ultra-violet can change direction when they cross the interface between two media.
Unique Properties
- Ultra-violet can cause electrons in some materials to gain enough energy to leave atoms creating ions which can destroy chemical bonds.
- Ultra-violet does not penetrate through the skin.
- Ultra-violet is scattered by the Earth's atmosphere.
Applications
- Ultra-violet can cause electrons in the atoms of fluorescent molecules to gain energy. When the electrons lose this energy they emit visible light. This can be used to reveal fluorescent ink to detect forged bank notes
- Ultra-violet causes damage to the skin by breaking chemical bonds so in an effort to protect itself the skin produces melanin, a brown pigment. This causes the skin to become tanned. This is used in tanning beds.
- Ultra-violet can destroy micro-organisms in water by breaking chemical bonds in those micro-organisms, so can be used to sterilise water.
Dangers
- Ultra-violet can cause sunburn and skin cancer by ionising and damaging DNA molecules in the skin cells leading to a mutation.
- Ultra-violet can cause cataracts as it damages the transparent protective layer on the eyes called the cornea.
References
AQA
- Ultraviolet (UV), pages 200, 207, 211, GCSE Combined Science Trilogy; Physics, CGP, AQA
- Ultraviolet (UV), pages 223, 225, 228, GCSE Combined Science; The Revision Guide, CGP, AQA
- Ultraviolet (UV), pages 242, 249, 251, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
- Ultraviolet (UV), pages 80, 81, GCSE Physics; The Revision Guide, CGP, AQA
- Ultraviolet light, page 121, GCSE Biology; Third Edition, Oxford University Press, AQA
- Ultraviolet radiation, pages 191, 197, 213, 218-19, 282, GCSE Physics; Student Book, Collins, AQA
- Ultraviolet radiation, pages 261, 266, 267-8, GCSE Combined Science Trilogy 2, Hodder, AQA
- Ultraviolet waves, page 196, GCSE Physics; Third Edition, Oxford University Press, AQA
- Ultraviolet waves, pages 194, 199, GCSE Physics, Hodder, AQA
- Ultraviolet; uses and applications, pages 200-1, GCSE Physics, Hodder, AQA
Edexcel
- Ultraviolet (UV) radiation, pages 74, 84, GCSE Physics, Pearson Edexcel
- Ultraviolet radiation, page 127, GCSE Physics, CGP, Edexcel
- Ultraviolet radiation; dangers, page 136, GCSE Physics, CGP, Edexcel
- Ultraviolet radiation; uses, page 134, GCSE Physics, CGP, Edexcel
- Ultraviolet, pages 168, 171, GCSE Combined Science; The Revision Guide, CGP, Edexcel
- Ultraviolet, pages 43, 47, GCSE Physics; The Revision Guide, CGP, Edexcel