Warm-Up ACT Question of the Day

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

Things to Know… Concept Symbol Units Period Frequency Wavelength Wave Speed Speed of Light

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 Medium vibrates at 90° to the direction of the wave Wave moves left to right, Medium goes up and down Shaking a Rope EM Waves (Light) end

Parts of a Wave end

Waves Wavelength Crest Amplitude Trough end

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

Waves end

Waves Compression Rarefaction Wavelength end

Properties of Waves end

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

Properties of Waves Crest Trough Rarefaction Compression Height/Top on a transverse wave Trough Lowest point on a transverse wave Rarefaction Where the medium is far apart on a longitudinal wave Compression Where the medium is close on a longitudinal wave Properties of Waves

Properties of Waves Period (T) Frequency (f) Time for 1 wave Frequency (f) Number of waves in 1 s Period and Frequency are inverses end

Properties of Waves Wavelength (λ) Distance between 2 identical points end

Properties of Waves Wave Speed (vw) end

Properties of Waves A wave has a frequency of 360 Hz. If its wavelength is 5 m, what wave’s speed? end

Practice A wave is moving with a velocity of 5 m/s. If its frequency is 2.5 Hz, what is the wavelength?

Practice 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?

Properties of Waves Wave Speed changes based on the medium, Fastest in Solids Slowest in Gases Because atoms in a solid are closer together end

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

To complete for Chapter 17 Complete wave worksheet and math review problems in your notes…TURN IN WHEN COMPLETE!!!

Bell Ringer: 12/2/14 HAVE YOUR REFERENCE TABLES OUT & CALCULATOR! What is the speed of light? If the wavelength is short, the frequency is low. True/False If the wave frequency is high, the wave energy is high. True/False What is the formula for Wave Speed? What are the units for frequency? Wavelength? Wave Speed? Calculate the following problem: If a wave is moving with a velocity of 12m/s, and a wavelength that measures 6m from crest to crest, what is the frequency?

Electromagnetic Spectrum

Electromagnetic Waves Electromagnetic (EM) Wave Transverse waves Electric and Magnetic Fields at 90° 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, as the Speed of Light (c) c = 3.0 x 108 m/s Since the speed is the same, 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? end

Practice A beam of visible light has a frequency of 4.5x1014 Hz. What is the wavelength of this light? What color is this light?

Practice 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?

Worksheet Speed of Light Practice Problems (1-5)

Electromagnetic Waves end

Electromagnetic Spectrum EM waves are divided based on their wavelength Energy Low High 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 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 Medicine and inspections Too much exposure can kill tissue Gamma Rays -STARS Have the shortest wavelength (highest frequency) Highest penetrating power, and highest energy end

Polarized Light – light vibrates in one direction Used in sunglasses Takes out glare end end 38

Passage of Light 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 39

The color seen, is reflected Other colors are absorbed Primary Colors: Red, Blue and Green The color seen, is reflected Other colors are absorbed Black- All colors are absorbed White- All colors are reflected end 40