CH 22/23 Mr. Jackson 5-3-12

Light is an EM wave (not requiring a medium)

EM waves are produced by radiation which is the transfer of energy in the form of a wave

What is Light

The Speed of Sound was 343m/sec The speed of light is 300,000,000m/sec This is 880,000 times faster than the speed

of sound If you could run at the speed of light you

could circumnavigate the earth 7.5 times per second

It takes 8.3 min for the sun to transmit light to the earth

Light Speed

The entire range of EM waves is called the EM spectrum

EM Spectrum

Longest Wavelength (over 30 cm) FM and AM radio and analog television

signals are broadcast using Radio waves

Radio Waves

Wavelength between 1mm and 30 cm Microwave ovens, Cell Phones and

Radar( Used to detect speed of a car) use microwaves.

Microwaves

Used to detect heat Military and Fire Kitchens to keep foodHot IR thermometer

Infrared

The only part of the EM Spectrum you can see.

The colors are Red, Orange, Yellow, Green, Blue, Indigo, Violet

Roy G. Biv

Visible light

More violet than violet (Ultra Purple) Commonly known as UV Tanning beds, black light, ect. UV CAUSES CANCER!!! UV Causes sunburn UV does allow the body to utilize vitamin D

Ultraviolet

Will pass through many materials Used in medical diagnostics Used for security devices in airports ect.

X Rays

Have the shortest wavelength Penetrate most materials easily Used for radiation treatment for cancer Also used to kill harmful bacteria in food

Gamma Rays

Light waves can be reflected by using a mirror

The law of reflection states that the angle of incidence is equal to the angle of reflection

Incidence is the arrival of a beam of light at a surface

Reflection

Objects that produce visible light are called luminous

Objects that are visible but do not produce light are called illuminated

Light Source vs. Reflection

When light becomes dimmer while traveling through a medium such as air is Absorption

Scattering is where light becomes dimmer due to the particles of light spreading out

Absorption and Scattering

Refraction of light is the bending of light This process occurs because light travels

slower through solids and liquids than it does air

Refraction will separate visible light into the 7 primary colors by using a prism

Refraction

A Transparent object allows light to be transmitted through the object (Glass)

A Translucent object transmits light but not an image ( Wax Paper)

An opaque object will not transmit light or an image

Types of Objects and their interaction with light

Red, Blue and Green are the Primary colors of light.

When the colors of light combine they undergo color addition which produce the secondary colors of light which are Magenta, Cyan, and Yellow

Television screens produce the colors Red, Blue and Green. New Televisions with 3-D Technology and LED Technology use Yellow in the pixels to produce more vibrant color schemes

When all the Primary colors mix they produce White light

Color

The primary pigments are Yellow, Magenta, and Cyan and by the process of color subtraction they produce the Primary Colors of light

When they all mix together they produce Black

Pigments

A plane mirror has a flat surface. Images appear the same size but are reversed right to left

Concave Mirror makes objects appear smaller shaped like the inside of a spoon

Convex Mirror Makes objects appear larger shaped like the back of a spoon

Mirrors

A lens is a transparent object that refracts light

Convex Lenses is thick in the middle and narrow on the edge. Used in magnifying lenses and in cameras

Concave Lenses are thin in the middle and thick on the edges. Used in eyeglasses and microscopes

Lenses

Nearsightedness is a condition where they eye is too long. These people see things up close but not far away

Farsightedness is there the eye is too short. These people can see far away but not up close

Color Blindness where the cones that receive color do not function properly

Vision Problems

Lasik is a surgical procedure where laser is used to reshape the lens of the eye. It is minimally invasive although the cornea is cut.

PRK is a surgical procedure that is used to reshape the lens. In this procedure the cornea is burned away by a laser and the recovery is longer however the correction tends to last longer

Surgical Eye Correction

Produces intense light of only 1 wavelength and color. The waves in a laser behave as 1 wave

Laser

Thin glass tubes that transmit light. Used for data and voice communication also

used for video Light in a pipe

Optical fiber

Polarized light is light that has passed through a filter and only 1 plane of the light is allowed to pass.

Polarized light