Electromagnetic Radiation and Its Importance

What is Electromagnetic Radiation?

• Odorless, tasteless, and invisible aspects of daily life
• Essential for the existence of our modern world

The Electromagnetic Spectrum

• Ranges from very short gamma rays to long radio waves
• Includes:
  • Gamma rays
  • X-rays
  • Ultraviolet rays
  • Visible light
  • Infrared waves
  • Microwaves
  • Radio waves
• Foundation of the information age

Uses of Electromagnetic Waves

• Radio
• Remote control
• Text messaging
• Television
• Microwave ovens
• Medical X-rays

Properties of Electromagnetic Waves

• Produced by the vibration of charged particles
• Have electrical and magnetic properties
• Travel through the vacuum of space at the speed of light
• Have crests and troughs like ocean waves
• Wavelength: distance between crests
• Frequency: number of crests passing a point per second, measured in Hertz
• Long waves (e.g., radio waves) have lower frequency and less energy
• Short waves (e.g., gamma rays) have higher frequency and more energy

Everyday Interaction with EM Waves

• Visible light waves from TV
• Radio waves from stations
• Microwaves for cell phones and WiFi
• GPS signals
• Chaos of various EM waves in any room

Perception of EM Waves

• Human eyes detect visible light (400-700 nanometers)
• Objects have color due to interaction with molecules and specific wavelengths
• Example: chlorophyll in leaves reflects green light (492-577 nm)

Scientific Exploration Beyond Visible Light

• Devices to detect and utilize different wavelengths
• Spectral signature: graph showing interactions across EM spectrum
• Identification of chemical composition and physical properties

Notable Uses in Science

• NASA's Spitzer space telescope: detecting water and organic molecules in distant galaxies
• SOHO satellite: studying the sun in multiple wavelengths, understanding sunspots and solar flares

Conclusion

• EM spectrum allows us to learn more about the world and universe
• Continuous discovery through different wavelengths