Lecture Notes: Light and the Electromagnetic Spectrum

Introduction to Visible Light

• Visible Light: Light that can be seen by the human eye.
  • Detected through the eyes, processed by the retina, and recognized as color.
  • Light travels in waves.

Properties of Visible Light

• Wavelength Range: 400 to 700 nanometers (nm).
  • Nano Prefix: Means "very small"; 1 nanometer = 1 billionth of a meter.
  • Violet light has shorter wavelengths (~400 nm) and red light has longer wavelengths (~700 nm).
• Colors and Wavelengths:
  • Violet, indigo, blue, green, yellow, orange, and red.

Electromagnetic Spectrum

• Definition: Range of all types of electromagnetic radiation.
  • Includes visible light and other types like x-rays, UV light, infrared, microwaves, and radio waves.
• Invisible Light: Cannot be detected by the human eye (e.g., x-rays, UV light, infrared, etc.).

Types of Electromagnetic Waves

• Gamma Rays: High energy, high frequency, short wavelength.
• X-rays and Ultraviolet: Higher energy, potential to damage.
• Infrared, Microwaves, Radio Waves: Lower energy, longer wavelength, less harmful.

Light Properties and Measurements

• Speed of Light: Denoted by "c"; 3 x 10^8 meters per second.
• Important Vocabulary:
  • Electromagnetic Radiation: Waves of energy.
  • Amplitude: Height of the wave.
  • Wavelength (λ): Distance between two peaks.
  • Frequency (ν): Number of peaks per second.
  • Peak/Crest: Top of the wave.
  • Trough: Bottom of the wave.

Relationship between Frequency and Wavelength

• High Frequency: Shorter wavelength, higher energy.
• Low Frequency: Longer wavelength, lower energy.

Visible Spectrum and Color

• Color and Wavelength:
  • Violet = ~400 nm
  • Green = ~500 nm
  • Orange = ~600 nm
  • Red = ~700 nm

Conclusion

• Bring any questions to your teacher in class for clarification.