Electromagnetic Electromagnetic SpectrumSpectrum

Light is a wave that we can Light is a wave that we can see.see.– Carries heat and warmthCarries heat and warmth– Has colorHas color– Travels 300,000,000 Travels 300,000,000

meters per second meters per second (5,880,000,000,000 miles (5,880,000,000,000 miles per year!)per year!)

– Can be bent by lens or Can be bent by lens or reflected by mirrors reflected by mirrors

What is What is light?light?

The The electromagnetic electromagnetic spectrum.spectrum.– The light we can see is The light we can see is

only a small part and only a small part and its called visible lightits called visible light

Lowest energy=radio Lowest energy=radio waveswaves

Highest Highest energy=gamma raysenergy=gamma rays

What is the What is the whole range of whole range of light called?light called?

What is the What is the lowest energy of lowest energy of the spectrum?the spectrum?

Highest levels of Highest levels of the spectrum?the spectrum?

Practice Makes Perfect!Practice Makes Perfect!

1. Which wave has the highest frequency?

a. Radio waves

b. Microwaves

c. X-rays

d. Gamma rays

2. Which wave has the lowest frequency?

a. Radio waves

b. Microwaves

c. X-rays

d. Gamma rays

3. Which wave has the highest energy?

a. Radio waves

b. Microwaves

c. X-rays

d. Gamma rays

4. Which wave has the lowest energy?

a. Radio waves

b. Microwaves

c. X-rays

d. Gamma rays

5. Which wave has the longest wavelength?

a. Radio waves

b. Microwaves

c. X-rays

d. Gamma rays

6. Which wave has the shortest wavelength?

a. Radio waves

b. Microwaves

c. X-rays

d. Gamma rays

Lowest frequency and Lowest frequency and energy of electromagnetic energy of electromagnetic wavewave– Transmit radio waves to your Transmit radio waves to your

radioradio– Tuner – adjusts radio to receive Tuner – adjusts radio to receive

a particular frequency of wavea particular frequency of wave

Used in some forms of Used in some forms of communicationcommunication– More commonly used to heat More commonly used to heat

food in the household food in the household microwavemicrowave

What are radio What are radio waves?waves?

What are What are microwaves?microwaves?

Infrared light emits heatInfrared light emits heat– Warmth from the sun, heat Warmth from the sun, heat

from your body, etc…from your body, etc… Used to make some medical Used to make some medical

diagnosesdiagnoses Night goggles – detect the Night goggles – detect the

infrared waves given off by infrared waves given off by warm bodieswarm bodies

Heat-sensitive alarm systems Heat-sensitive alarm systems react to infrared waves being react to infrared waves being given off by a warm objectgiven off by a warm object

Used to keep your food warm in Used to keep your food warm in a restauranta restaurant

What are What are infrared infrared lights?lights?

The only part of the The only part of the electromagnetic electromagnetic spectrum that you spectrum that you can seecan see

includes a rainbow of includes a rainbow of colors from low to colors from low to high energy.…high energy.…

ROYGBIVROYGBIV

RedRed, , OrangeOrange, , YellowYellow, , GreenGreen, , BlueBlue, , IndigoIndigo, , VioletViolet

What is visible What is visible light?light?

What are the What are the colors we see colors we see in the visible in the visible spectrum?spectrum?

Comes from the sun Comes from the sun Exposure helps skin Exposure helps skin

cells to produce cells to produce vitamin D which helps vitamin D which helps promote healthy bones promote healthy bones and teethand teeth

Overexposure can kill Overexposure can kill healthy cells, cause healthy cells, cause saggy or dry skin, and saggy or dry skin, and cause cancercause cancer

Earth’s ozone layer is a Earth’s ozone layer is a natural protector that natural protector that blocks most of the blocks most of the sun’s UV rayssun’s UV rays

What are What are ultraviolet ultraviolet light?light?

Can travel through Can travel through more matter such as more matter such as your skin and your skin and muscles, but not muscles, but not bonebone– Have higher frequency and Have higher frequency and

more energy than more energy than ultraviolet radiationultraviolet radiation

– Used to examine your Used to examine your bones and teeth in the bones and teeth in the doctor’s officedoctor’s office

– Used to scan luggage at the Used to scan luggage at the airportairport

– Overexposure can be Overexposure can be dangerousdangerous

What are What are x-rays?x-rays?

Emitted from the nuclei Emitted from the nuclei of radioactive atoms.of radioactive atoms.– Have the highest frequency Have the highest frequency

and are the most and are the most penetrating of all penetrating of all electromagnetic waveselectromagnetic waves

– Can be concentrated and Can be concentrated and used to kill cancerous cells, used to kill cancerous cells, but cause extreme side but cause extreme side effects such as fatigue, effects such as fatigue, nausea, and hair lossnausea, and hair loss

– Technicians and doctors Technicians and doctors must monitor their intake of must monitor their intake of gamma radiation and gamma radiation and protect themselves by protect themselves by standing behind a lead standing behind a lead shield whenever possibleshield whenever possible

What are What are gamma gamma rays?rays?

Light and the color of Light and the color of objects as they reflect objects as they reflect or absorb determines or absorb determines what color you see.what color you see.

In order for you to see In order for you to see an object, it must an object, it must reflect some light.reflect some light.– White objects appear White objects appear

white because they reflect white because they reflect all colors in the visible all colors in the visible spectrumspectrum

– Black objects absorb all Black objects absorb all colors of light and reflect colors of light and reflect very little lightvery little light

How do we How do we see color?see color?

The photoreceptors in the retina The photoreceptors in the retina respond to the different energies respond to the different energies of light in the visible spectrumof light in the visible spectrum

Our eyes have two different types Our eyes have two different types of photoreceptors: of photoreceptors: rod cells and rod cells and cone cells.cone cells.– The 3 cone cells respond to The 3 cone cells respond to

color: red for red and yellow, color: red for red and yellow, green for yellow and green, and green for yellow and green, and blue for blue and violetblue for blue and violet

– Rod cells respond only to Rod cells respond only to differences in brightness and differences in brightness and are useful for seeing in dim lightare useful for seeing in dim light

How do we How do we see?see?

So…So…

When you look at a yellow banana, When you look at a yellow banana, both red and green cones respond both red and green cones respond by absorbing yellow light and your by absorbing yellow light and your brain interprets it as “yellow”brain interprets it as “yellow”

People who have People who have color blindnesscolor blindness have difficulty distinguishing have difficulty distinguishing between some colors because one between some colors because one or more cones does not function or more cones does not function properlyproperly

The primary pigments The primary pigments are are cyancyan, , magentamagenta, and , and yellowyellow. These colors are . These colors are the result of the the result of the absorption of one of the absorption of one of the primary colors of light.primary colors of light.– The reason a blue cloth The reason a blue cloth

looks blue is because the looks blue is because the pigment in the cloth pigment in the cloth absorb all the frequencies absorb all the frequencies of light other than blue.of light other than blue.

– Since blue are all that is Since blue are all that is left, they are the ones that left, they are the ones that are reflected to our eyes.are reflected to our eyes.

What are the What are the 3 primary 3 primary pigments?pigments?

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