ELECTROMAGNETIC WAVES

ELECTROMAGNETIC WAVES

Electromagnetic waves are made from moving charges (protons or electrons)

EM waves are transverse waves The medium that EM waves pass through

are electric and magnetic fields Electric field

Produced by electrically charged particles and by changing magnetic fields.

Magnetic field Produced by magnets, by changing electric fields,

and by vibrating charges

ELECTROMAGNETIC WAVES

They carry energy from one place to another The transfer of energy using EM waves is

called electromagnetic radiation The electric field oscillates in one direction The magnetic field oscillates perpendicular

to the electric field

Both the electric and magnetic fields oscillate perpendicular to the direction of travel

EM waves are broken up into categories based on their frequency

TRAVELING

Do not need a medium Can travel through a vacuum, or empty

space, as well as through matter EM waves traveling through matter or

across space is called electromagnetic radiation.

Changing electric fields produce changing magnetic fields and vice versa Fields regenerate each other

SPEED

EM waves travel the same speed when in a vacuum

Speed of light in a vacuum is 3.00 x 108 m/s

Remember- all EM waves travel at the same speed in a vacuum but they are not all the same!!!!!

WAVELENGTH AND FREQUENCY

Speed = wavelength x frequency Remember-waves are going to travel at

the same speed What is changing then? Wavelength and frequency are inversely

proportional Wavelength increases, frequency decreases Wavelength decrease, frequency increases

INTENSITY

Rate at which a wave’s energy flows through a given unit of area

Brightness of a light Intensity of a light will decrease as

photons travel farther from the source

ELECTROMAGNETIC SPECTRUM

Radio

Microwaves

Infrared

Ultraviolet

Gamma Rays

X-Rays

Frequency & Energy Increases

Wavelength Increases

Visible Light

VISIBLE LIGHT

Red Violet

ROY G. BIVed

range

el low

reen

lue

ndigo

iolet

Red 610-750 nm Blue 450-500 nm

Orange 590-610 nm Violet 400-450 nm

Yellow 570-590 nm Green 500-570 nm

Radio Waves Radio waves are used to transmit radio

and television signals, as well as cell phone conversations

RADAR RADAR stands for Radio Detection and Ranging

Uses radio waves and the Doppler shift to measure how fast something is moving

Infrared Waves Infrared waves are heat waves The human body gives off heat in the form of

infrared waves We sense infrared waves as heat

Visible Light The part of the electromagnetic spectrum that

we can see is the visible light Ultraviolet Waves (UV)

UV waves are what cause you to tan Excessive UV rays can cause you to sunburn,

wrinkle, and eventually skin cancer UV rays can also be used to disinfect air

X-Rays Can be used to see a person’s skeleton Can also be used to see inside packages,

suitcases, or tractor trailers

Gamma Rays

Have the shortest wavelength and the most energy

Exposure to tiny amounts is tolerable, but overexposure is deadly

They are used in medicine to kill cancer cells and take pictures of the brain

Used in industry to examine a tool for weaknesses or defects

COLOR Sir Isaac Newton

In 1666, conducted his first experiments with prisms

When he shone light through a prism, he produced an ordered arrangement of colors, from red to violet

He called this sequence of colors a spectrum Found that white light is composed of colors

Color by Addition Primary Colors of Light

Red Green Blue

Combining the correct amount of the primary colors of light to produce different colors is called the additive color process

Secondary Colors of Light Magenta Cyan Yellow

Red

Blue

Green

Yellow

Magenta

Cyan

Color by Subtraction Pigment and Dye absorb certain colors and

reflect others Reflected colors are the colors that we see Making colors by absorbing different colors is

called a subtraction process Primary Pigment – Absorbs one primary color of

light Yellow Cyan Magenta

Secondary Pigment – Absorbs two primary colors of light

Red Blue Green

Red

Blue

Green

Yellow

Magenta

Cyan