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Light Waves

Light Waves. The Electromagnetic Spectrum. What is Light?. A difficult question, thousands of years in understanding. Very difficult to study, since it cannot be caught, and it is very difficult to measure. What is Light?.

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Light Waves

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  1. Light Waves

  2. The Electromagnetic Spectrum

  3. What is Light? • A difficult question, thousands of years in understanding. • Very difficult to study,since it cannot becaught, and it is verydifficult to measure.

  4. What is Light? • Light is a wave that travels through the universe’s electromagnetic field. • Electromagnetism = a combination of electricity and magnetism • Light waves do notneed a physical medium like air.

  5. Properties of Light • Frequency – light is caused by the vibrations of electrons • Wavelength – light waves have crests and troughs, just like water waves • Speed – the speed of light depends on what it is traveling through.

  6. Speed of Light (in a vacuum) • 299, 792, 485 m/s ≈ 3 x 108 m/s • 186,282 miles per second • 671 million miles per hour • Can be slowed if passing through water, glass, etc.

  7. Types of Light • Most light is invisible, because it has frequencies that our eyes cannot see. • Light with faster frequencies has shorter wavelengths and higher energy • Speed = wavelength x frequency • Wavelength = 3 x 108 m/s÷ frequency

  8. Types of light

  9. Types of light

  10. Types of light

  11. A Spectrum is a continuous range

  12. Another Diagram

  13. Notice this backwards (?) diagram

  14. The NECAP Version

  15. It’s a Spectrum! • The only difference between types of light is how fast it vibrates (frequency) • Radio waves, visible light, and x-rays are all waves created by vibrating electrons at different speeds

  16. Light can act like a wave! • It can reflect! Reflection = bouncing off

  17. Light can act like a wave! • It can refract! Refraction = bending when it passes through

  18. Light can act like a wave! • It can disperse! Dispersion = separating frequencies of light

  19. Light can act like a wave! • It can diffract! Diffraction = spreading out and separating (by frequency)

  20. Summary 1/3 • Light is a wave. • Light has frequency and wavelength. • The speed of light in a vacuum is 3 x 108 m/s. • It is the second fastest thing in the universe (only bad news travels faster).

  21. Summary 2/3 • There are many types of light, which all differ only by frequency/wavelength • Faster frequency = shorter wavelength = more energy • In order: Radio, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma Rays

  22. Summary 3/3 • Light reflects (bounces off of objects), like on a mirror • Light refracts (bends while passing through objects), like through a glass • Light diffracts (spreads out and separates by wavelength), like making a rainbow

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