Electromagnetic Spectrum and Colors

The EM Spectrum

• Speed of all electromagnetic waves is constant = speed of light

• High Frequency = Small Wavelength = High Energy– Gamma Rays

• Low Frequency = Large Wavelength = Low Energy– Radio Waves

Energy

Radio Waves• Wavelengths

– 30 cm to longer than our planet

• Sources– Stars– Transmitters

• Uses– AM Radio = Amplitude Modulation– FM Radio = Frequency Modulation– Television– Cell phones– Radar

Energy

Microwaves• Wavelengths

– 30 cm to 1 mm

• Sources– Stars– Magnetron

• Uses– In microwave ovens– Cell phones, GPS– Wi-Fi– Doppler Radar (Weather

maps)– Radar

Energy

Infrared Waves• Wavelengths

– 1 mm to 700 nm

• Sources– Stars– Organisms– Heat Sources

• Uses– Night Vision– Thermal Imaging– Remote Controls

Energy

Visible Light• Region of the EM spectrum that the human eye can detect• All the colors (ROYGBIV - this is order of colors in increasing energy /

decreasing wavelength / increasing frequency)• Wavelengths

– 700 nm to 400 nm• Sources

– Stars– Light Bulbs– Lasers

• Uses– Sight– Communication

R O Y G. B I V

red orange yellow green blue indigo violet

Energy

Ultraviolet Waves• Wavelengths

– 400 nm to 60 nm

• Sources– Stars– Black Lights (UVA)– Mercury-Vapor Lamps (UVB and UVC)

• Uses– Sterilization– Security– Forensics– Chemical Markers

• UVA = tanning, wrinkles• UVB = tanning, sunburn, cancer• UVC = used for sterilization, most dangerous

Energy

X-Rays• Wavelengths

– 60 nm to 0.0001 nm

• Sources– Stars– X-Ray Tubes

• Uses– Medical Imaging– Security– Astronomy

• Can penetrate soft tissue, but not bone

Energy

Gamma Rays• Wavelengths

– 0.1 nm to 0.00001 nm

• Sources– Radioactive atoms (radioactive

waste from nuclear fission plants releases gamma rays)

– Stars

• Uses– Cancer radiation treatments Radiation treatment using

radioactive cobalt-60.

Light and Color• Opaque

– Absorbs or reflects all light (can’t see through it)

• Translucent– Allows some light to pass

through it

• Transparent– Allows light to pass through

completely

Additive Color• White light

– contains all visible colors - ROYGBIV

• In white light, an object…– reflects the color you see– absorbs all other colors

• Primary Additive Colors– Red– Green– Blue

• Examples– Computer Monitors (kinda)– Televisions (kinda)

Subtractive Color• Pigments, Dyes, Inks, Paints

– colored material that absorbs and reflects different colors

• Primary Subtractive Colors– Magenta– Cyan– Yellow

• Examples– Color Ink Cartridges

Negative Afterimage - One set of cones gets tired, and the remaining cones produce an image in the

complimentary color.

Exit Ticket: #9-12

9. What type of electromagnetic radiation has the longest wavelength?A.Gamma raysB.MicrowavesC.Light wavesD.Radio waves

10. What type of electromagnetic radiation has the highest frequency?A.Gamma raysB.MicrowavesC.Ultraviolet wavesD.Radio waves

11. What type of electromagnetic radiation has the most energy?A.Radio wavesB.X-raysC.Infrared wavesD.Gamma Rays

12. What color has the SHORTEST wavelength?A.VioletB.YellowC.RedD.Green