Chapter 5: Ray Model of Light
Ray Model of Light:
Represents the path taken by light
Light moves in straight lines
Speed in a vacuum:
Luminous objects generate their own light (e.g., bulbs, candles)
Non-luminous objects reflect light (e.g., bike reflectors, wooden table)
Principles and Applications of Light Reflection:
Reflection allows us to see objects
Lateral Inversion: Mirror reverses left and right
Image properties with plane mirrors:
Same size as the object
Upright but virtual
Image and object distances are equal
Applications: decoration, periscopes, optical testing, mirrors in vehicles
Ray Diagrams for Reflection:
Locate image by equal distance from the surface
Draw light rays as straight lines
Use dotted lines for unreal paths
Include a normal line and arrows for light direction
Symmetry in object and image distances
Types of Reflection:
Regular Reflection: occurs on smooth surfaces, clear images
Diffused Reflection: occurs on rough surfaces, no sharp images
Specialized Mirrors:
Concave Mirrors: inward bending, virtual and magnified images, used for makeup/shaving
Convex Mirrors: outward bending, wider field of vision, distorted images, used in vehicles
Mechanics of Light Refraction:
Refraction: light bending when passing into a new medium
Depends on optical density
Causes visual distortions (e.g., apparent depth)
Ray diagrams: dotted lines for perceived paths and solid lines for actual paths
Dispersion of White Light:
White light is a mixture of colors
Dispersion splits light into a spectrum via a prism
Formation of rainbows; dispersion is reversible
Societal and Environmental Impacts of Radiation:
Technology benefits and drawbacks
Infrared: used in thermal imaging, heat impacts climate change
Ultraviolet: vital for Vitamin D, causes skin cancer from overexposure
Visible light: essential for photosynthesis, contributes to light pollution