HAPPY WEDNESDAY! • Today’s Objec.ve: PSc.3.2.2 Compare waves (mechanical and electromagne;c) using characteris;cs such as wavelength & frequency • Lesson Overview: Take notes & listen to lecture; fill in guided notes & prac;ce; complete “sta;ons” ac;vity; play Kahoot to review & be assessed for today’s lesson
NOTEBOOKS • Glue in today’s guided notes on pg. 103 in your notebooks & think about the review prompt below • Review Prompt/Ques.ons: – What do mechanical waves need to travel through? – How can we describe the mo;on of mechanical waves? (using terms from yesterday’s lesson)
Electromagnetic Waves • Mechanical waves need a medium to travel through, like solids, liquids, or gases – Electromagne.c waves can travel through empty space (vacuum)
Electromagnetic Waves • Electromagne.c waves are transverse waves consis;ng of changing electric fields and changing magne;c fields o Like mechanical waves, EMs carry energy from place to place • EWs differ from MWs in how they are produced and how they travel
Electromagnetic Waves • EMs are produced by constantly changing fields • An electric field is produced by electrically charged par;cles & by changing magne;c fields
• EMs can travel through a vacuum, or empty space, as well as through maUer
Electromagnetic Waves • The transfer of energy by electromagne;c waves traveling through maUer or across space is called electromagne.c radia.on • The full range of frequencies of electromagne;c radia;on is called the electromagne.c spectrum
Electromagnetic Waves • Radio waves have the _longest ______ wavelength in the spectrum & _lowest _____ frequencies • Gamma waves have the _shortest ______ wavelength in the spectrum & highest ______ frequencies
Electromagnetic Spectrum
Electromagnetic Waves • The only part of the EM spectrum we can see is visible light
EVERYDAY ENCOUNTERS
Match the wave to its description D B A E C G F
FREQUENCY RADIAT ION
ENERGY
WAVELENGTH
RADIO
MICRO
INFRARED
U.V.
X-RAY GAMMA
RED ORANGE YELLOW GREEN BLUE INDIGO VIOLET
CHART PG. 104 Card Descrip.on # of image
1 2 3 4 5 6 7 8 9 10
Type of EM wave
Radia.on/ Danger?
Sta.on cards #1-‐10
#1.
#2.
#3.
#4.
#5.
#6.
#7.
#8.
#9.
#10.
Card #
CHART PG. 104 KEY
Descrip.on of Type of image EM wave
1
Radio tower
2
Sun’s rays burning child Microwave warming food Catscan scanning for cancer Hands being x-‐rayed
3 4 5
Radia.on/Danger?
Radio wave
Low radia;on; low energy
U.V.
Mid radia;on; fairly high frequency; can cause skin cancer
Microwave
Low danger/risk; long wavelength
Gamma
High risk; high energy & frequency
X-‐ray
Can be dangerous; 2nd highest frequency; penetrates skin
6
Elephant shown using a thermogram
Infrared
Low radia;on risk
7
Rainbow
Visible
Low risk; only part we can see
8
Heat lamp for food
9
cellphones
infrared Radio & microwave
Low radia;on risk Low risk; considered background radia;on
10
Airport security bag scanner
X-‐ray
Can be dangerous; 2nd highest frequency & a lot of energy