Why Objects Appear the Color They Do

Visible Light and Color Spectrum

• Visible Light: Comprises a spectrum of colors from red to violet.
  • Red: Longest wavelength, lowest frequency.
  • Violet: Shortest wavelength, highest frequency.
• ROYGBIV: Acronym to remember the order of colors in the spectrum.
• White Light: Combination of all wavelengths.
• Blackness: Absence of light.

Factors Determining Object Color

• Wavelengths of Light: What light hits the object.
• Object Properties: How the object interacts with light.
• Resulting Color: Depends on which light rays are absorbed, reflected, or transmitted.

Opaque Objects

• Definition: Do not transmit light (e.g., a cat).
• Color Determination: Based on reflected wavelengths.
  • Example: An object appears blue by reflecting blue wavelengths and absorbing others.
  • Some objects reflect a range of wavelengths that combine to produce a certain color (e.g., yellow cheese might reflect red and green).

Transparent and Translucent Objects

• Transparent Objects: Transmit nearly all light (e.g., window glass).
• Translucent Objects: Transmit some light, affecting visibility.
  • Color depends on which wavelengths are transmitted most (e.g., a green bottle transmits green wavelengths).

Color Filters

• Purpose: Filter out particular colors by transmitting certain light wavelengths.
• Primary Color Filters: Allow one of the primary colors (red, green, blue) to pass through.
  • Example: A green filter only lets green wavelength pass, making white paper appear green.
  • A blue object's color would not pass through a green filter, appearing black.
• Non-primary Color Filters: Let through wavelengths of the filter's color and those of primary colors that combine to make it.
  • Example: Yellow filters let through yellow, red, and green wavelengths (since red + green = yellow).
  • Indigo filters allow indigo, blue, and red wavelengths (since blue + red = indigo).

These points summarize the key concepts of why objects appear the color they do, focusing on the interaction of light and object properties, and the role of color filters.