Bellringer: 5/14/2018 What do you already know about waves? Draw a wave in your notebook. Where can you find waves? STOTD

Things to know… Concept Symbol Units Period T Seconds (s) Frequency f Hertz (Hz) or 1/s Wavelength λ Meters (m) Wave Speed Vw Meters/Second (m/s) Speed of Light c

Waves, Sound, and the Electromagnetic Spectrum Chapter 17 and 18

Waves Mechanical Wave A disturbance in matter that carries energy Created by a vibration Must travel through a medium Air, water, land, metal, … Cannot travel through a vacuum (like space!) 2 types: Transverse and Longitudinal end

Waves Transverse Waves The medium vibrates at right angles to the direction of the wave Wave moves left to right, Medium goes up and down Shaking a Rope Electromagnetic Waves end

Waves Wavelength Crest Amplitude Trough end

Waves Longitudinal (Compression) Waves The medium vibrates parallel to the direction of the wave Wave moves left to right Medium moves left to right A Spring Sound end

Waves Compression Rarefaction Wavelength Amplitude end

Properties of Waves end

Properties of Waves Amplitude How much the medium is moved Bigger Amplitude = More Energy end

Properties of Waves Crest The top on a transverse wave Trough The bottom on a transverse wave Compression Where the medium is close together on a longitudinal wave Rarefaction Where the medium is further apart on a longitudinal wave

Properties of Waves Period (T) Frequency (f) Time for 1 wave to occur Measured in seconds (s) Frequency (f) Number of waves in 1 s Measured in Hertz (Hz) Period and Frequency are inverses of each other end

Properties of Waves Wavelength (λ) Distance between 2 identical points on a wave Example: Crest to crest or trough to trough end

BILL NYE THE SCIENCE GUY!! https://www.schooltube.com/video/2b2001da6d8146dbb388/Bill%20Nye%20-%20Waves Look at your worksheet! Read the questions before we watch the video

Properties of Waves Wave Speed (vw) Measured in meters/seconds (m/s) end

Properties of Waves A wave has a frequency of 360 Hz. If its wavelength is 5 m, what wave’s speed? A wave is moving with a velocity of 5 m/s. If its frequency is 2.5 Hz, what is the wavelength? The speed of light is 3.0 x 108 m/s. Blue light has a wavelength of 4.5 x 10-7 m, what is its frequency? end

Properties of Waves Wave Speed changes based on the medium, Fastest in Solids Slowest in Gases Because atoms in a solid are closer together Light is the Exception The speed of light = 3.0 x 108 m/s end

Sound Waves Sound is a Longitudinal Wave Intensity (Loudness) Pitch More Amplitude = Louder Decibels (dB) Pitch High Frequency = High Pitch end

Electromagnetic Waves Electromagnetic (EM) Wave Transverse waves with an electric field and a magnetic field at 90° to each other end

Electromagnetic Waves Created by moving electric charges Does Not need a medium to travel Can travel through empty space EM Radiation Transfer of energy by EM waves end

Electromagnetic Waves All EM waves travel at the same speed, the Speed of Light (c) c = 3.0 x 108 m/s Since the speed is the same, Different EM waves have different frequencies and wavelengths As frequency goes up, wavelength goes down High Frequency = High Energy end

Electromagnetic Waves If the speed of a wave is: Then the speed of an EM wave is: Speed of Light (3.0x108 m/s) end end

Electromagnetic Waves A gamma ray has a wavelength of 7 x 10-13 m. What is the frequency of this ray? A satellite transmits on the EM Spectrum at a frequency of 9.4 x 109 Hz. What is the signal’s wavelength? What type of wave is being transmitted? A beam of visible light has a frequency of 4.5x1014 Hz. What is the wavelength of this light? What color is this light? end

Bellringer: A gamma ray has a wavelength of 5 x 10-13 m. What is the frequency of this ray? A wave is moving with a velocity of 10 m/s. If its frequency is 2.5 Hz, what is the wavelength? STOTD

Electromagnetic Spectrum EM waves are divided based on their wavelength Energy Low High end

Electromagnetic Waves end

Electromagnetic Spectrum Radio Waves Longest wavelengths Radio and TV Microwaves Cooking food and Radar Only penetrates a few centimeters Infrared (IR) Rays Felt as heat Given off by warm objects end

Electromagnetic Spectrum Visible Light What we can see To remember the colors in order use: ROY-G-BIV Red, orange, yellow, green, blue, indigo, violet Ultraviolet (UV) Rays Helps your body produce Vitamin D to absorb calcium Used to kill bacteria end

Electromagnetic Spectrum X-Rays Used in medicine, and for inspection of objects Too much exposure can kill tissue Gamma Rays Have the shortest wavelength (highest frequency) Highest penetrating power, and highest energy end

Polarized Light – light vibrates along a single plane Moving in one direction Used in sunglasses end end 30

Light passes through without interruption A Window Translucent Transparent Light passes through without interruption A Window Translucent Light passes through, but is scattered Wax-Paper or Frosted Glass Opaque Light cannot pass through A Wall. end 31

The color you see is being reflected by the object Primary Colors: Red, Blue and Green The color you see is being reflected by the object All other colors are being absorbed Black- All colors are absorbed White- All colors are reflected end 32