Light - 02 - Reflection - Laws of Reflection

University:
High School
Course:
High School Physics
Academic year:

2024
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302

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11
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6.1 Reflection Types & Laws of Reflection Light:  If the object is: ⚫ Opaque: the transmission is interrupted  ⚫ Transparent or translucent: passes through, but path is bent (refraction)  ⚫ Ex. window, frosted glass, water Reflective: does not pass through, is reflected back   Ex. piece of wood Ex. Mirror, calm water, shiny metals Reflection: The change in direction of light after meeting a surface that returns light to its original medium Types of Reflection:  Specular Reflection: ⚫ ⚫ ⚫ Light reflected “perfectly” (in parallel to each other) from a shiny, polished surface… Ex. mirrors, stainless steel, glass, polished metals, calm bodies of water Wavelength of the light is greater than the size of the surface irregularities.  Diffuse Reflection: ⚫ ⚫ ⚫ Light reflected “irregularly” (in different directions) from an irregular surface Ex. Sheet of paper, table top Size of the surface irregularities is greater than or equal to the light’s wavelength Light and Reflection:   The change in direction of light after meeting a surface that returns light to its original medium Can be: - Specular: Reflects light perfectly, forms sharp images - Diffuse: Reflects light irregularly, does not form images 6.2 Laws of Reflection – Plane Mirror: incident ray normal reflected ray angle of angle of reflection incidence i r 90 0 point of incidence   The angle of incidence is equal to the angle of reflection The incident ray, the reflected ray & the normal all lie in the same plane. Ex. Given the plane mirrors, draw the reflective rays. i = 18o i = 49o  r = 49o  r = 18o 6.3 Curved Mirrors:   A spherical mirror may be thought of as a section of a hollow sphere The inside of the sphere results in a concave mirror ⚫  also called a converging mirror The outside results in a convex mirror ⚫ also called a diverging mirror Laws of Reflection – Curved Mirrors:  Same as plane mirrors, but must construct the normal using the tangent to the curve of the mirror at the incidence point point of incidence tangent  incidence  reflection i =  r normal Ex Given the curved mirror, draw the reflective ray. i = 10o  r = 10o Quantum: HW: pg 43 #1, 2 & 6 pg 45 #1 & 3 pg 47 #1, 2, 4, 5 & 7