Visible light is electromagnetic radiation with wavelengths

from 400 to 700 nm.

The electromagnetic spectrumIncludes more that just

Visible light.

An electromagnetic wave isA transverse wave consisting

Of oscillating electric andMagnetic fields at rightAngles to each other.

Electromagnetic waves varyDepending on frequency and wavelength, this is

Called the spectrum.

Classification Applications

Radio Waves AM or FM radio and television

Microwaves Radar, Microwaves ovens

Infrared Waves Heat, photography, physical therapy

Visible Light Seeing, photography

Ultraviolet Light Sterilization

X-Rays Medical Exams

Gamma Rays Cancer Treatment

All electromagnetic wavesMove at the speed of light.

c = f λ

C = 2.998 X 108

The AM radio band extends From 5.4 X 105 Hz to

1.7 X 106 Hz. What are the Longest and shortest wavelengths

In this frequency range?

560 m and 180 m

A luminous body is one thatEmits light waves.

An illuminated body simply Reflects light waves produced

From an outside source.

Waves can be approximated As rays for easier drawing

And visualization.

Brightness decreases by the Square of the distance from

The source. This is called the inverse

Square law.

The Candela is the SI base unitOf luminous intensity,

It is also called a candle power.

Luminous flux (P) is the rate at Which light is emitted from a

Source.

A lumen is a unit of Luminous flux.

Illuminance (E) is the rate at whichLight falls on a surface.

Lux is a unit of illuminance,Lumens per square meter.

E = P4πd2

What is the illumination onYour desktop if it is lighted by A 1750 lm lamp that is 2.5m

Above your desk?

E = 22.3 lx

In 1665, Francesco Grimaldi Observed that the edges of a

Shadow are not perfectly sharp.

He also noted that the shadowWas bordered by colored bands.

Grimaldi recognized this Phenomenon as diffraction,

Which is the bending of lightAround a barrier.

Additive primary colors produceWhite light when combined.

Subtractive primary colorsFilter out all light when combined.

A primary color is a color from Which all other colors

Can be derived.

A secondary color formed by A pair of two primary colors.

A complementary color is two Colors of light which when added

Together produce white light.

A dye is a molecule that absorbsSome light wavelengths andReflects or transmits others.

A pigment is a colored materialThat absorbs certain colors And reflects or transmits

Other colors.

A primary pigment is a pigment That absorbs only one color

from white light.

A secondary pigment is a pigment that absorbs two primary Colors from white light.

Thin-film interference is light Interference caused by reflection From the front and back surface

Of a thin layer of liquid.

Color

All visible colored light together produce white light (ex. sunlight).

• White is not a single color, but a combination of all colors.

• White objects reflect all colors.

Black is not a single color – it is the absence of light.

• Black objects absorb all frequencies of light.

• They reflect only enough light so that you can see them.

• An object’s color depends on which light frequencies are reflected and which are absorbed.

– Ex: A blue shirt appears blue because it absorbs all colors EXCEPT blue. It reflects the blue back to our eyes.

– Ex: A plant leaf is green because it absorbs all the colors BUT green to use for photosynthesis.

Linear polarization is the Alignment of electromagneticWaves in such a way that the Vibrations of the electric fields

In each of the waves are Parallel to each other.