Drill: Calculate the speed of a water wave when waves 5 Drill: Calculate the speed of a water wave when waves 5.0 m apart pass by at 40.0 waves per minute

Chapter 16 Light

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

An ordered arrangement of many frequencies or wavelengths of waves Spectrum An ordered arrangement of many frequencies or wavelengths of waves

Electromagnetic Spectrum An ordered arrangement of all the electromagnetic waves

The straight line path of a light wave Ray The straight line path of a light wave

A ray striking a surface Incident Ray A ray striking a surface

A ray passing through a substance Transmitted Ray A ray passing through a substance

A ray bouncing off of another 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.

For most calculations: Speed of Light cvac = 299,792,458 m/s For most calculations: c = 3.00 x 108 m/s

Light Velocity Formula: c = lf

Calculate the frequency of electromagnetic waves at: 600 Calculate the frequency of electromagnetic waves at: 600.0 nm 150 mm 45.0 cm

Calculate the frequency of IR light at: 900.0 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

The unit of luminous flux 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

The illumination of a surface Illuminance (E) The illumination of a surface

Lux (lx) The unit for illumination lx = lm/m2

Luminous Intensity (I) The magnitude of the light source

Candle power of the unit for luminous intensity Candela (cd) Candle power of the unit for luminous intensity

Luminous Intensity Formula d2 E =

Luminous Flux Formula P 4pd2 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 Calculate the illumination on a surface 2.0 m away from a bulb emitting 1600 cd.

Calculate the illumination on a surface 3 Calculate the illumination on a surface 3.0 m away from a bulb emitting 2700 cd.

Substances that allows light to be clearly transmitted through them Transparent Substances that allows light to be clearly transmitted through them

Translucent Substances that allows light to be transmitted, though not clearly, through them

Substances absorb or reflect all light striking 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

Colors produced by mixing primary colors Secondary Colors Colors produced by mixing primary colors

Secondary Colors Yellow = Red + Green Cyan = Blue + Green Magenta = Red + Blue

Two colors that when mixed produced white light 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 l, ¾ l, 5/4 l, etc

Electromagnetic waves are transverse with vibrations like sin waves vibrating at 360o from the ray

A light wave vibrating in only one direction Polarized Light A light wave vibrating in only one direction

Can be produced by passing regular light through a polarized lens Polarized Light Can be produced by passing regular light through a polarized lens

A screen with very fine slits all being parallel to each other 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