Chapter: Light, Shadows and Reflections

• Light

  • Definition: Form of energy that enables us to see
  • Luminous Objects
    • Emit their own light
    • Examples: Sun, torch, firefly
  • Non-Luminous Objects
    • Do not emit light; reflect light from other sources
    • Examples: Moon, tree, book
  • Types of Materials based on Light
    • Transparent: Allow light to pass through completely (e.g., clear glass)
    • Translucent: Allow light to pass through partially (e.g., butter paper)
    • Opaque: Do not allow light to pass through at all (e.g., wooden block)

• Shadows

  • Definition: Dark patches formed when an opaque object blocks the path of light
  • Necessary Conditions for Formation
    • Source of light
    • Opaque object
    • Opaque screen (wall, ground)
  • Characteristics of Shadows
    • Always dark, regardless of object's color
    • Provide only the outline or shape, not details
    • Size varies with the distance between light source, object, and screen

• Pinhole Camera

  • Simple device to demonstrate light travels in a straight line
  • Principle: Rectilinear propagation of light
  • Characteristics of Image Formed
    • Inverted (upside down)
    • Real and colored

• Mirrors and Reflections

  • Reflection Definition: Bouncing back of light from a polished or shiny surface
  • Plane Mirror
    • Forms clear and exact images
    • Shows lateral inversion (left appears right)
  • Difference between Image and Shadow
    • Shadow: Only black outline, lacks details
    • Image: Has colors, details, and exact features of the object