electromagnetic spectrum - clarkparkway.com · fields also vibrate, producing an electromagnetic...

Electromagnetic Spectrum

Unit 3 Lesson 3  

Unit 3 Lesson 3 The Electromagnetic Spectrum

Florida Benchmark

Copyright © Houghton Mifflin Harcourt Publishing Company

•  SC.7.P.10.1 Illustrate that the sun’s energy arrives as radiation with a wide range of wavelengths, including infrared, visible, and ultraviolet, and that white light is made up of a spectrum of many different colors.

Waves… a review

 Most waves are either longitudinal or transverse.

 Sound waves are longitudinal.  But all electromagnetic waves

are transverse…

Electromagnetic Light Show


What is the nature of light?

•  Light waves are different from other kinds of waves.

•  When an electrically charged particle vibrates, its fields also vibrate, producing an electromagnetic (EM) wave.

•  Light waves are vibrating electric and magnetic fields that transfer energy through space.


Electromagnetic waves  Produced by the movement of

electrically charged particles  Can travel in a “vacuum” (they do

NOT need a medium  Travel at the speed of light

 Also known as EM waves

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

a particle  A “particle” of light is called a photon


•  EM waves travel as perpendicular electric and magnetic fields.




•  Radiation is energy that has been transmitted by waves or particles. This transfer of energy is called EM radiation.

•  All EM waves move at the same speed in a vacuum: the speed of light.

•  EM waves can travel through many materials.



What determines the color of light?

•  Different wavelengths of light are perceived by our eyes as different colors.

•  White light is what we perceive when we see all the wavelengths of light at once, in equal proportions.

•  Our eyes only register three colors of light: red, green, and blue. All other colors we see are a mixture of these three colors.



Invisible Colors


What are the parts of the EM spectrum?

•  The range of frequencies that EM waves can have are called the electromagnetic (EM) spectrum.


Radio waves  Longest wavelength EM waves  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   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

Ultraviolet  Shorter wavelengths than visible

light  Uses:

  Black lights   Sterilizing medical equipment   Water disinfection   Security images on money

Ultraviolet (cont.) UVA UVB and UVC

Energy Highest of UV waves

Lower than UVA

Health risks

  Extremely low risk for DNA damage   Can destroy Vitamin A in skin

  Can cause DNA damage, leading to skin cancer   Responsible for sunburn

X-rays  Tiny wavelength, high energy waves

 Uses:   Medical imaging   Airport security   Inspecting industrial welds

Gamma Rays  Smallest wavelengths, highest

energy EM waves  Uses

  Food irradiation   Cancer treatment   Treating wood flooring

Star Light, Star Bright


How much of the sun’s energy reaches us? •  Most of the sun’s energy is in the narrow visible

light range, but the sun gives off some radiation in every part of the spectrum.


How much of the sun’s energy reaches us? •  Not all wavelengths of light penetrate the

atmosphere equally. Radio waves penetrate the atmosphere easily.



How much of the sun’s energy reaches us? •  Some EM radiation can be dangerous to humans,

so we take extra steps to protect ourselves.

•  UV light can be harmful. It can penetrate clouds.

•  In space, the dangers from EM radiation are very high because there is no atmosphere to filter the radiation.



Frequency Asked Questions


How much energy does EM radiation have? •  Different frequencies of EM waves carry different

amounts of energy.

•  High-frequency EM waves have more energy than low-frequency EM waves.


How much energy does EM radiation have? •  Because low-frequency waves, such as radio

waves, carry less energy, they are safer. Walkie-talkies and baby monitors use radio waves.

•  High-frequency waves, such as UV light, carry more energy and can be harmful. UV light causes sunburns, and X-rays require precautions.




Fire in the Sky


•  The stream of electrically charged particles from the sun is called the solar wind.

•  When solar wind encounters Earth’s magnetic field, the particles are accelerated.

•  When the accelerated particles collide with the atmosphere, they give off EM radiation in the form of light.


Fire in the Sky


•  Near the poles, the accelerated particles form an aurora that can light up the sky.

•  The aurora at the North Pole is called the aurora borealis. At the South Pole, it is called the aurora australis.

•  The color of the aurora depends on the type of atoms in the atmosphere that react with the solar wind.

electromagnetic spectrum - clarkparkway.com · fields also vibrate, producing an electromagnetic...

Documents