Electromagnetic Spectrum

Light is a wave that we can see. Light is a wave that we can see. –Carries heat and warmth – Has color –Travels 300,000,000 meters per second (5,880,000,000,000 miles per year!) –Can be bent by lens or reflected by mirrors What is light? What is light?

The electromagnetic spectrum. The electromagnetic spectrum. –The light we can see is only a small part and its called visible light Lowest energy=radio waves Lowest energy=radio waves Highest energy=gamma rays Highest energy=gamma rays What is the whole range of light called? What is the whole range of light called? What is the lowest energy of the spectrum? What is the lowest energy of the spectrum? Highest levels of the spectrum? Highest levels of the spectrum?

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 energy of electromagnetic wave Lowest frequency and energy of electromagnetic wave –Transmit radio waves to your radio –Tuner – adjusts radio to receive a particular frequency of wave Used in some forms of communication Used in some forms of communication –More commonly used to heat food in the household microwave What are radio waves? What are radio waves? What are microwaves? What are microwaves?

Infrared light emits heat Infrared light emits heat –Warmth from the sun, heat from your body, etc… Used to make some medical diagnoses Used to make some medical diagnoses Night goggles – detect the infrared waves given off by warm bodies Night goggles – detect the infrared waves given off by warm bodies Heat-sensitive alarm systems react to infrared waves being given off by a warm object Heat-sensitive alarm systems react to infrared waves being given off by a warm object Used to keep your food warm in a restaurant Used to keep your food warm in a restaurant What are infrared lights? What are infrared lights?

The only part of the electromagnetic spectrum that you can see includes a rainbow of colors from low to high energy.… ROYGBIV Red, Orange, Yellow, Green, Blue, Indigo, Violet What is visible light? What is visible light? What are the colors we see in the visible spectrum? What are the colors we see in the visible spectrum?

Comes from the sun Comes from the sun Exposure helps skin cells to produce vitamin D which helps promote healthy bones and teeth Exposure helps skin cells to produce vitamin D which helps promote healthy bones and teeth Overexposure can kill healthy cells, cause saggy or dry skin, and cause cancer Overexposure can kill healthy cells, cause saggy or dry skin, and cause cancer Earth’s ozone layer is a natural protector that blocks most of the sun’s UV rays Earth’s ozone layer is a natural protector that blocks most of the sun’s UV rays What are ultraviolet light? What are ultraviolet light?

Can travel through more matter such as your skin and muscles, but not bone Can travel through more matter such as your skin and muscles, but not bone –Have higher frequency and more energy than ultraviolet radiation –Used to examine your bones and teeth in the doctor’s office –Used to scan luggage at the airport –Overexposure can be dangerous What are x-rays? What are x-rays?

Emitted from the nuclei of radioactive atoms. Emitted from the nuclei of radioactive atoms. –Have the highest frequency and are the most penetrating of all electromagnetic waves –Can be concentrated and used to kill cancerous cells, but cause extreme side effects such as fatigue, nausea, and hair loss –Technicians and doctors must monitor their intake of gamma radiation and protect themselves by standing behind a lead shield whenever possible What are gamma rays? What are gamma rays?

Light and the color of objects as they reflect or absorb determines what color you see. Light and the color of objects as they reflect or absorb determines what color you see. In order for you to see an object, it must reflect some light. In order for you to see an object, it must reflect some light. –White objects appear white because they reflect all colors in the visible spectrum –Black objects absorb all colors of light and reflect very little light How do we see color? How do we see color?

The photoreceptors in the retina respond to the different energies of light in the visible spectrum The photoreceptors in the retina respond to the different energies of light in the visible spectrum Our eyes have two different types of photoreceptors: rod cells and cone cells. Our eyes have two different types of photoreceptors: rod cells and cone cells. –The 3 cone cells respond to color: red for red and yellow, green for yellow and green, and blue for blue and violet –Rod cells respond only to differences in brightness and are useful for seeing in dim light How do we see? How do we see?

So… When you look at a yellow banana, both red and green cones respond by absorbing yellow light and your brain interprets it as “yellow” When you look at a yellow banana, both red and green cones respond by absorbing yellow light and your brain interprets it as “yellow” People who have color blindness have difficulty distinguishing between some colors because one or more cones does not function properly People who have color blindness have difficulty distinguishing between some colors because one or more cones does not function properly

The primary pigments are cyan, magenta, and yellow. These colors are the result of the absorption of one of the primary colors of light. The primary pigments are cyan, magenta, and yellow. These colors are the result of the absorption of one of the primary colors of light. –The reason a blue cloth looks blue is because the pigment in the cloth absorb all the frequencies of light other than blue. –Since blue are all that is left, they are the ones that are reflected to our eyes. What are the 3 primary pigments? What are the 3 primary pigments?

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