Light & Optics Chapters 14-16

Electromagnetic Wave

Speed of Light in a vacuum, c = 3 x 10 8 m/s for all waves, v = f for light, c = f

Brightness of Light inverse square law

Light Rays travel in a straight line in a uniform medium can bend in a non-uniform medium reflect and refract at boundaries between mediums

Reflection diffuse reflectionspecular reflection

Law of Reflection

Ray Diagrams

Plane (flat) Mirror Light rays appear to originate behind the mirror (virtual image) Left/Right reversal Distance from object to mirror (s o ) = Distance from image to mirror (s i ) Height of object (h o ) = Height of image (h i )

Ray Diagram for Plane Mirror

Spherical Mirrors

Focus f = focal length (distance from mirror to focus) R = radius of curvature (distance from mirror to center) R = 2f

Mirror Equation: Magnification Equation: M = magnification (unitless)

Sign Conventions +s i = real image -s i = virtual image +h = upright -h = inverted +f for concave mirrors -f for convex mirrors M>1 = image is enlarged M<1 = image is reduced

Ray Tracing: Concave Mirror

Refraction Refraction – the bending of light as it travels from one medium to another. – This happens because the speed of light changes when the medium changes.

Index of Refraction n = c/v n = index of refraction v = speed of light in the medium

Index of refraction is affected by wavelength – shorter wavelengths bend more

Refraction Through Glass Slab

Lenses

Lens Equations

Sign Conventions +s i = real image -s i = virtual image +h = upright -h = inverted +f for converging lens -f for diverging lens M>1 = image is enlarged M<1 = image is reduced -M = inverted

Ray Tracing: Lenses

Polarization

No light

Color Depends on wavelength Color of an object is the wavelength it reflects

Additive Color - Light

Subtractive Color – Pigments

Are You Colorblind?