Chapter 5 The Ray Model of Light Mirrors

Chapter 5 ~ The Ray Model of Light, Mirrors, & Lenses Lesson 5. 1 ~ The Ray Model of Light

DESCRIBING LIGHT v Wave Model (chapter 4) – light travels as a wave v Particle Model - light source releases particles that perfectly enter the eye v Ray Model (chapter 5) – light is represented as a ray, or straight line

THE RAY MODEL OF LIGHT

LIGHT AND MATTER v The type of matter in an object determines the amount of light it reflects, absorbs, and transmits

v Transparent material allows light to pass through it freely v Objects can be clearly seen through the material v Example: Clear windows

v Translucent material allows most light rays through but scatters the light v Objects can NOT be clearly seen v Example: Frosted glass in bathroom windows

v Opaque material allows NO light to get through v Objects can not be seen at all v Example: Concrete wall

Transparent Translucent Opaque

Ray Diagrams & Shadows

LIGHT CAN BE REFLECTED v In order for something to act as a mirror and reflect an image, it has to be perfectly smooth

THE LAW OF REFLECTION v Light rays hit a mirror and bounce off (reflect off) v The incoming ray is called the incident ray v The outgoing ray is called the reflected ray

v The incident ray and the reflected ray on either side of a line called the normal v The normal is an imaginary line that is perpendicular to the boundary

v The angle made by the incident ray and the normal is called the angle of incidence ( i) v The angle made by the reflected ray and the normal is called the angle of reflection ( r) v ( i) is always equal to ( r) v This is called the Law of Reflection

LIGHT CAN BE REFRACTED v Light bends when it moves into different mediums v Light bends because the speed changes v The angle of refraction is the angle between the refracted ray of light and the normal