Calculate the speed of a water wave when waves 5.0 m apart pass by at 40.0 waves per minute
Chapter 16 Light
The range of frequencies of electromagnetic waves that stimulate the retina of the eye
Electromagnetic Wave Transverse waves made up of pulses moving through space that affect both electric & magnetic fields
Spectrum An ordered arrangement of many frequencies or wavelengths of waves
Electromagnetic Spectrum An ordered arrangement of all the electromagnetic waves
Ray The straight line path of a light wave
Incident Ray A ray striking a surface
Transmitted Ray A ray passing through a substance
Reflected Ray A ray bouncing off of another substance
Speed of Light First Determined by Ole Roemer by observing the moons of Jupiter from opposite ends of Earth’s orbit.
Speed of Light Correctly determined by Michelson by reflecting light from a spinning octagonal mirror.
Speed of Light c vac = 299,792,458 m/s For most calculations: c = 3.00 x 10 8 m/s
Light Velocity Formula: c = f
Calculate the frequency of electromagnetic waves at: nm 150 m 45.0 cm
Calculate the frequency of IR light at: nm
Luminous Anything that emits light Sun, light bulb, etc
Illuminated Anything that reflects light Moon, mirror, wall, etc
Luminous Flux (P) The rate at which light is emitted
Lumens (lm) The unit of luminous flux
Light from a bulb or source is emitted spherically from the source
We are usually interested in the illumination of a certain area
Illuminance (E) The illumination of a surface
Lux (lx) The unit for illumination lx = lm/m 2
Luminous Intensity (I) The magnitude of the light source
Candela (cd) Candle power of the unit for luminous intensity
Luminous Intensity Formula I d 2 E =
Luminous Flux Formula P 4 d 2 E =
Determine the effect on illumination of a wall if a light source is moved from 30.0 to 120 cm away from the wall.
Calculate the illumination on a surface 2.0 m away from a bulb emitting 1600 cd.
Calculate the illumination on a surface 3.0 m away from a bulb emitting 2700 cd.
Transparent Substances that allows light to be clearly transmitted through them
Translucent Substances that allows light to be transmitted, though not clearly, through them
Opaque Substances absorb or reflect all light striking them
Color A perception caused when cones in the eyes are excited by certain frequencies or wavelengths of electromagnetic waves
Luminous Colors
Primary Colors Red Blue Green
Secondary Colors Colors produced by mixing primary colors
Secondary Colors Yellow = Red + Green Cyan = Blue + Green Magenta = Red + Blue
Complimentary Colors Two colors that when mixed produced white light
Complimentary Colors Red + Cyan Blue + Yellow Green + Magenta
List the three primary colors & list each’s complementary color.
Illuminated Colors
Dyes Molecules that absorb certain wavelengths of light; thus reflect others
Dyes Dyes are made up of molecules which are too small to be seen with a microscope
Dyes When dissolved, form colored solutions that allow light to pass through
Pigments Materials that absorb certain wavelengths of light; thus reflect others
Pigments Pigments are made up of particles large enough to be seen with a microscope
Pigments When dissolved, form suspensions that reflect light and are opaque
Primary Pigments A pigment that absorbs a primary color
Primary Pigments Yellow Cyan Magenta
Secondary Pigments A pigment that absorbs two primary colors; thus reflect the third
Secondary Pigments They are the primary colors: red, blue, & green
Thin Film Interference Constructive & destructive effects of interference causing a rainbow appearance on a thin film
Thin Film Interference Wavelengths are reinforced when the film is ¼, ¾, 5/4, etc
Electromagnetic waves are transverse with vibrations like sin waves vibrating at 360 o from the ray
Polarized Light A light wave vibrating in only one direction
Polarized Light Can be produced by passing regular light through a polarized lens
Polarizer A screen with very fine slits all being parallel to each other
Calculate the frequency & period of light with a wavelength of 450 nm