Waves, sound, Electromagnetic Radiation Conceptual Physics
To do… See how many of the quiz topics you can answer as a table group (if you don’t know the answer right away, seek out the answer with your notes/webquests/EM poster) Identify which questions your table can’t answer Pick your top 2 topics that you need to review today…
Self-grade… Go over answers on your webquests 18 pts each answer
Shows example of a wave (indicating change in wavelengths) 2 Arrows showing areas of higher and lower wavelengths, frequencies and energy. 6 The six types of EM Waves discussed in class 6 Drawings/pictures that represent the type of wave 6 Accurate ratios and division of page2 Creative/Artistic/Colorful/Neat/Professional 5 Totals /27
4 square notes 5 pts each page Definition = 1 Real world ex = 2 Picture = 1 3-5 facts = 2 Total = 30 pts Radio Infrared Visible light Uv X-rays Gamma rays
Next 10 minutes Interactive review Do NOT write for next 10 minutes Stop – share with table group all the information you think is important for quiz, what information was clarified for you
Wave Basics Key Vocab. -Amplitude: The maximum displacement of a wave from equillibrium (height of a wave) -Wavelength: The length of one full wave cycle or repetition -Period: The amount of time it takes a wave to complete one full cycle -Frequency: The number of wave vibrations/repetitions per second (Hz) -Equilibrium: The resting place of a wave with no disturbance -Crest: The highest point or peak of a wave -Trough: The lowest point or bottom of a wave Crest Trough Line of Equilibrium
Basics Waves- traveling disturbance that carries energy (not matter) Boat/wave example Energy = ability to do work Vibration: any movement follows same path repeatedly Ear drum, drum, earthquake
Vibrate – particle moving – produces energy – transfers energy to nearby particles – wave Ocean, ropes, sound, microwaves
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Waves… a review Most waves are either longitudinal or transverse. Sound waves are longitudinal. But all electromagnetic waves are transverse…
Wave Types A wave is a traveling disturbance that transfers energy. 2 Types of Waves: Transverse: side to side wave sending vibration perpendicular to the medium Longitudinal: push & pull wave sending vibration parallel to the medium Parallel Vibration Perpendicular Vibration Direction of Energy
Amplitude = amount of energy Frequency = number of waves in given time (Hz – 1 Hz=1 wave/sec)
Speed of wave Speed = freq x wavelength (λ) Depends on medium its traveling in Density (moves slower) – more inertia Elasticity (faster) – faster in solid than liquid/gas temperature
Write these notes down…
Key Vocab for Wave interactions Reflection – bouncing back of a wave after it strikes a boundary that does not absorb all the wave’s energy Ray is a line drawn to show direction of a wave and show wave activity Incident – incoming wave Reflected wave – wave being bounced back
Refraction – bending of waves due to a change in speed (occurs because waves move at different speeds in different mediums) – air to water, glass to air
Diffraction – bending of waves around the edge of an obstacle The amount of diffraction depends on the wave length and the size of obstacle Snowball vs. yelling
Interference – When 2 or more waves arrive at the same place at the same time – they combine to form a single wave Constructive = combine (larger amplitude) Destructive = cancel (no wave)
What wave interaction is happening to the spoon in the water?
What type of wave interaction is this? Car headlights with open eyes Car headlights with squinted eyelashes
What type of wave interaction is this?
w_0media_physics/hewittvideos/dop pler.html w_0media_physics/hewittvideos/dop pler.html
As a table Summarize what the doppler effect is Be ready to share
Doppler Apparent change in pitch caused by motion As moving towards me, pitch is higher As moving away from me, pitch is lower
Electromagnetic Spectrum
Wavelength and the Spectrum
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
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.) UVAUVB and UVC EnergyHighest 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
Image credits 1. education.co.uk/New_items/MUS/images/Making6.gif education.co.uk/New_items/MUS/images/Making6.gif 2. in12.jpg in12.jpg ctrum.jpg ctrum.jpg headset.jpg headset.jpg on%20goggles.jpg on%20goggles.jpg network.com/direct/dbimage/ /Study_Remote_Control.jpg network.com/direct/dbimage/ /Study_Remote_Control.jpg SM%20brand%20imagemed.jpg SM%20brand%20imagemed.jpg
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