Notes on Electromagnetic Waves and Radiation

Overview

• Discusses generation and absorption of electromagnetic radiation.
• Describes hazards of ultraviolet, x-rays, and gamma rays.
• Explains radio wave production (for higher-tier students).

Generation and Absorption of Electromagnetic Waves

• Key Fact: Changes in atoms or nuclei cause electromagnetic wave generation or absorption.
  • Heating lithium: Electrons move to higher energy levels, then return, emitting light (electromagnetic wave).
• Electromagnetic Wave Production:
  • Electrons moving between energy levels generate waves.
  • Nuclei changes, e.g., gamma rays from radioactive nuclei.
  • Gamma rays emission reduces nucleus energy.
• Wave Absorption:
  • Absorption can also cause electron energy level changes.
  • Waves emitted and absorbed over a wide frequency range (radio to gamma rays).

Hazards of Electromagnetic Radiation

• Ultraviolet Waves:
  • Increases skin cancer risk and causes premature skin aging.
• X-rays and Gamma Rays:
  • Ionizing radiation that knocks electrons off atoms.
  • Causes gene mutations, increasing cancer risk.
• Radiation Damage:
  • Depends on radiation type and dose.
  • Measured in sieverts or millisieverts.
  • Not required to remember units for exam but may need to interpret data.

Production of Radio Waves (Higher-Tier)

• Radio Wave Production:
  • Produced by electron oscillation in electrical circuits.
  • Oscillation: Electrons move back and forth.
  • Absorbed by aerial circuits, causing electron oscillation.
  • Creates alternating current with same frequency as radio waves.

Additional Resources

• Mention of a revision workbook for further study on this topic.