Lecture Notes on Beta Carotene and Color Perception

Introduction to Beta Carotene

• Beta carotene is a molecule responsible for the orange color of carrots.
• It has a dot structure that can be examined to understand its properties.

Absorption Spectrum of Beta Carotene

• Beta carotene absorbs light in the visible region of the electromagnetic spectrum.
• Visible region begins around 400 nm:
  • Left of 400 nm: UV region
  • Right of 400 nm: Visible region
• Beta carotene absorbs wavelengths approximately between 450 to 500 nm.

Visible Region and Color

• The visible spectrum encompasses colors of the rainbow:
  • 400 nm: Violet
  • 700 nm: Red
  • Beyond violet: UV region
  • Beyond red: Infrared region
• Colors listed: Red, Orange, Yellow, Green, Blue, and Violet.
• Notably, Isaac Newton included indigo to have seven colors (ROYGBIV).

Color Wheel and Complementary Colors

• A color wheel arranges colors to show relationships between complementary colors:
  • Red complementary to Green
  • Violet complementary to Yellow
  • Blue complementary to Orange

Perception of Color

• Why objects appear a certain color:
  • White light is composed of all rainbow colors.
  • Simplified model: white light = complementary color pairs.
  • Example: Orange object absorbs blue wavelengths, reflects orange wavelengths.
  • Our eyes perceive the object as orange because of reflected orange light.

Beta Carotene and Color Perception

• Beta carotene absorbs blue wavelengths (450-500 nm), reflecting orange wavelengths.
• Thus, it appears orange to our eyes.

Upcoming Topics

• Next video will explore how the dot structure of beta carotene contributes to its color properties.