PRESENTATION OF GROUP 1 REGARDING ULTRAVIOLET LIGHT

UV Rays

1. Group 1 Presentation Ultraviolet (UV) Light Applications • Vocabulary • Definition • Discoverer

2. Vocabulary (Key Terms) 1. Ultraviolet (UV) – Radiation beyond violet light. 2. Wavelength – Distance between two wave peaks. 3. UVA, UVB, UVC – Types of UV light. 4. Disinfection – Killing harmful microorganisms. 5. Radiation – Energy traveling as waves.

3. Definition Ultraviolet (UV) light is electromagnetic radiation with wavelengths between 10–400 nanometers. It is invisible to the human eye and lies between visible light and X-rays.

4. Discoverer • Discovered in 1801 by Johann Wilhelm Ritter. • Observed invisible rays beyond violet that darkened silver chloride paper. • Originally called 'chemical rays,' later named ultraviolet rays.

5. Types of UV Light • UVA (320–400 nm): Least harmful, causes skin aging. • UVB (280–320 nm): Causes sunburn, helps produce vitamin D. • UVC (100–280 nm): Very harmful, used in sterilization, absorbed by atmosphere.

6. Applications 1. Medicine – Treats skin diseases, produces vitamin D. 2. Disinfection – UVC kills bacteria, viruses, fungi. 3. Forensics – Detect fingerprints, bodily fluids, fake money. 4. Astronomy – Studying stars and cosmic radiation. 5. Industry – UV lamps for curing adhesives, inks, and resins.

7. Benefits & Risks ✅ Benefits: Vitamin D, sterilization, medical uses. ⚠️ Risks: Skin cancer, eye damage, premature aging if overexposed.

8. Conclusion • UV light is a powerful tool discovered in 1801. • Widely used in medicine, industry, and science. • Must be used carefully due to potential health risks.

9. References • Physics textbooks on Electromagnetic Spectrum • ScienceDirect articles on UV Applications • National Aeronautics and Space Administration (NASA) • World Health Organization (WHO) – UV Radiation Facts