electromagnetic spectrum #1

Electromagnetic Radiation

S8P5:

Students will explore the wave nature of sound and electromagnetic radiation.

Science Standard

What are some everyday uses of electromagnetic radiation (or waves)?

Essential Question

Waves… a reviewMost waves are either

longitudinal or transverse.Sound waves are longitudinal.But all electromagnetic waves

are transverse…

?

?

Electromagnetic waves Produced by the movement of

electrically charged particles

Can travel in a “vacuum” (they do NOT need a medium)

Electromagnetic waves Travel at the speed of light

(300,000,000 m/s in a vacuum )* Travels slower when passing through a medium

Also known as EM waves because they are surrounded by:

i.Electric fields ii.Magnetic fields

Wave-particle Duality Light can behave like a wave or like a

particle Travels in bundles of energy Bundles act like small particles

A “particle” of light is called a photon

Wave-particle Duality

All electromagnetic waves travel at the same speed

Frequency and wavelength are used to classify the waves in the electromagnetic spectrum

Wave-particle Duality

ElectromagneticSpectrum

The electromagnetic spectrum is the complete range of electromagnetic waves placed in order of increasing frequency.

ElectromagneticSpectrum

ElectromagneticSpectrum

As the frequency increases: a.Wavelength decreases b.Photon penetrating energy increases

Radio waves Longest wavelength EM wavesLow Frequency & Lowest Photon Energy Uses:

TV broadcasting AM and FM broadcast radio Avalanche beacons Heart rate monitors Cell phone communication

Microwaves Wavelengths from 1 mm- 1 m Uses:

Microwave ovens Bluetooth headsets Broadband Wireless Internet Radar GPS

Infrared Radiation Wavelengths in between microwaves

and visible light Uses:

Night vision goggles Remote controls Thermal Energy Transfer Heat-seeking missiles

Visible light Only type of EM wave able to be

detected by the human eye Violet is the highest frequency light Red light is the lowest frequency light Only EM we can see

Ultraviolet Shorter wavelengths & higher

frequency than visible light Uses:

Black lights Sterilizing medical equipment Water disinfection Produces vitamin D in human skin Security images on money

X-rays Tiny wavelength, high energy waves – greaterpenetrating power Uses:

Medical imaging Airport security Inspecting industrial welds

Gamma Rays Smallest wavelengths, highest

energy EM waves Uses

Food irradiation Cancer treatment Treating wood flooring

Light and Color

Type of matter in an object determines the amount of light it absorbs and reflects.

___ water ___ gray rock ___ leaf ___ mirror ___ glass ___ sand ___ potato skin ___ wax paper ___ tomato soup ___ crumpled paper ___ shiny metal ___ dull metal

___ red apple ___ rough cardboard ___ the Moon ___ rusty nail ___ clouds ___ soil ___ milk ___ bedsheet ___ brand new penny ___ wood ___ old tarnished penny ___ smooth sheet of aluminum

foil

Can it Reflect Light?What types of objects or materials can reflect light? Put an X next to the things you think can reflect light.Explain your thinking. Describe the “rule” or the reasoning you used to decide if something can reflect light.

Light and Color

1.Opaque materials – absorbs or reflects all light, you can not see through them

2.Transparent materials – allow light to pass through, you can see through them

3.Translucent materials – allow some of the light to pass through; you can not clearly see objects through them

Visible Light Spectrum

Light waves in the visible spectrum arranged from longest wavelength to

shortest wavelength.

Red Orange Yellow Green Blue Indigo Violet

Light and Color

The color appearance of any object is due to the wavelengths of light that are reflected from the object

and picked up by our eyes.

Light and Color1.White reflects all the colors of the visible spectrum.

2.Black objects absorb all the colors of the visible spectrum.

Lenses Bend Light Lenses are used in microscopes,

telescopes, binoculars, cameras, magnifying glasses, and eyeglasses.

The Refraction of Light When light travels from some

transparent substances through others –like air into water or glass into air, the light bends.

Convex LensesConcave LensesPrisms

Convex Lenses A magnifying glass is an example of

a convex lens. A convex lens is thicker in the middle

of the lens than it is at the ends. A convex lens bends the light and

makes the object look larger or magnify it.

Concave Lenses

A concave lens is thinner in the middle than at the ends.

Concave lenses cause the light to spread out after light passes through them.

Concave lenses are used in glasses for people who are short-sighted or cannot clearly see things far away.

Prisms A prism bends the light in such a

way that it separates it into different parts.

Normal white light contains all the colors of the rainbow.

Prisms can separate the different colors because each color bends differently when it passes through a prism.