Labs and Activities for this Presentation: NOTE: This presentation was not made for public use. Please do not use this presentation without my permission and the permission of each of the authors of the photographs, quotes, and other materials that they contain. Thank you, Vicki Hughes Labs and Activities for this Presentation: Prism Demo

wAVES

WAVES OF SOUND AND LIGHT Electromagnetic Waves = can travel through a vacuum Example: light waves Mechanical Waves = must have a medium to travel in Example: sound waves

Characteristics of Waves Crest = top of a wave Trough = bottom of a wave Wavelength is the distance from crest to crest

Characteristics of Waves Amplitude is the distance from resting to the top or bottom of a wave. amplitude rest amplitude

Characteristics of Waves Frequency is the number of waves that pass a fixed point in a given amount of time. 3 4 2 1 5 seconds

Properties of Waves Wave Speed = Wavelength x Frequency The speed of a wave is a product of its wavelength and frequency. What is the formula for Wave Speed? Wave Speed = Wavelength x Frequency What is the formula for Frequency? Wave Frequency = Speed Wavelength

Properties of Electromagnetic Waves Example Problem: An electromagnetic wave has a wavelength of 3 meters and a speed of 3.0 x 108 m/s. What is its frequency? Wave Frequency = Speed Wavelength Wave Frequency = 3.0 x 108 m/s = 1. 0 x 108 Hz 3 m

Transverse waves = move perpendicular to the path of travel. Types of Waves Transverse waves = move perpendicular to the path of travel. perpendicular Longitudinal Wave Longitudinal waves = move parallel to the path of travel. parallel

Sound is Mechanical Remember, mechanical waves must have a medium through which they move. This medium can be solid…

Sound is Mechanical This medium can be liquid…

Light & Sound This medium can be gaseous…

If a tree falls in the forest and nobody is around to hear it, does it make a sound?

Characteristics of Sound All sounds begin with vibrating matter.

Characteristics of Sound Ear captures vibrations. How do we hear sounds? Guitar string vibrates. Vibration is transferred to air particles and move away from the string in waves. Auditory Transduction 6:44 http://www.youtube.com/watch?v=PeTriGTENoc&feature=related

Characteristics of Sound Remember, sounds cannot travel through space…because there is no medium. http://www.ck12.org/book/CK-12-Physical-Science-For-Middle-School/r2/section/19.1/

Characteristics of Sound Properties of Sound: SPEED Speed of Sound = the distance that sound travels in a given amount of time. Sound travels more slowly than light. BOOM!

Characteristics of Sound Sounds travels faster in liquids than in gases… and faster in solids than in liquids.

Characteristics of Sound Loudness is determined by sound intensity. Intensity is a measure of the amount of energy in sound waves. Unit of intensity = decibel (dB)

Characteristics of Sound Pitch of Sound = how high or low a sound seems to a listener. Waves and Pitch 2:00 http://www.curriculumbits.com/?s=pitch

Characteristics of Sound Pitch depends on the frequency of sounds. Frequency = how often something happens The frequency of waves is the number of waves that pass a fixed point in a given amount of time.

Characteristics of Sound Unit for frequency = hertz (Hz) Humans can hear frequencies between 20 – 20,000 Hz.

Characteristics of Sound Doppler Effect = change in frequency when sound waves are moving. Example: As a train approaches it becomes louder and louder, then as it leaves you it becomes softer and softer.

Electromagnetic Waves Electromagnetic radiation is the transfer of energy by waves traveling through matter or across empty space. Electromagnetic waves consist of vibrating electric and magnetic fields.

Electromagnetic Waves ACT L18 Electromagnetic waves do NOT require a medium… So electromagnetic waves can travel through space.

Behavior of Waves Electromagnetic waves can also travel through matter just like mechanical waves. They can: Reflect (bounce back) This property is called reflection.

Electromagnetic Waves Electromagnetic waves travel through matter just like mechanical waves. They can: Refract (bend through objects) This property is called refraction. Light through a prism 3:22 http://www.youtube.com/watch?v=KgqV975EtA0 Demo: Prism

Electromagnetic Waves Electromagnetic waves travel through matter just like mechanical waves. They can: Diffract (bend around objects) This property is called diffraction.

Electromagnetic Waves Electromagnetic waves travel through matter just like mechanical waves. They can: be transmitted (sent from one place to another) This property is called transmission.

Electromagnetic Waves Electromagnetic waves travel through matter just like mechanical waves. They can: be absorbed (gathered in by an object) This property is called absorption. Absorbed light

Electromagnetic Waves Electromagnetic waves travel through matter just like mechanical waves. They can: scatter (deviate from their original path) This property is called scattering.

Electromagnetic Waves Electromagnetic waves act like waves most of the time, But sometimes…They act like particles!

Electromagnetic Waves Photon = energy released when electromagnetic radiation acts like particles and drops to a lower atomic level.

Electromagnetic Waves The amount of energy in a photon depends on the frequency of the electromagnetic wave that produced it.

Types of Electromagnetic Waves Electromagnetic Spectrum is the full range of wavelengths.

Types of Electromagnetic Waves Radio Waves lowest frequencies used for radio and television broadcasts, microwave ovens, cell phone transmissions, and radar

Types of Electromagnetic Waves Light Waves Includes visible light, infrared light, and ultraviolet light. UV infrared Visible Light

Types of Electromagnetic Waves Light Waves can be separated using a triangular prism.

Types of Electromagnetic Waves Visible Light The only light that humans can see. Visible Light http://www.ck12.org/book/CK-12-Physical-Science-For-Middle-School/r2/section/20.3/

Any Questions? ACT L19 only #1 and #3. EOG CH 2 Review Light Drawing https://www.youtube.com/watch?v=Bfn69oMuH4E