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Recognize that all waves transfer energy. R e l a t e f r e q u e n c y & w a v e l e n g t h t o t h e e n e r g y o f d i f f e r e n t t y p e s o f e l e c t r o m a g n e t i c w a v e s & m e c h a n i c a l w a v e s. C o m p a r e a n d c o n t r a s t t h e c h a r a c t e r i s t i c s o f e l e c t r o m a g n e t i c a n d m e c h a n i c a l ( s o u n d ) w a v e s. E x p l a i n t h e p h e n o m e n a o f r e f l e c t i o n, r e f r a c t i o n, i n t e r f e r e n c e, & d i f f r a c t i o n. E x p l a i n t h e D o p p l e r E f f e c t i n t e r m s o f e v e r y d a y i n t e r a c t i o n s. Relate the speed of sound to different mediums. 2

Waves  Waves are disturbances that carry energy through matter or space. Clip Clip  The material does not actually travel with the wave….. only the energy is carried.  Waves can be visible or invisible evidence of energy transfer. 3

Types of Waves Two types of waves: Mechanical Non-Mechanical Mechanical: waves need a medium in order to travel. Examples: Sound, water Non-mechanical: waves do not need a medium to travel. Examples: light, gamma waves, microwaves, x-rays 4

Waves that require a medium to travel. Light waves are NOT Mechanical Waves. Sound and water. Mechanical Waves A medium is the material a wave travels through 5

Ways that waves travel Transverse waves –Water, light Longitudinal waves –sound 6

Transverse Waves  Transverse waves are UP & DOWN movements. EX: water waves, radio waves (all EM waves)  The displacement of individual particles is perpendicular (at right angles) to the direction of the wave. 7

Describing a Transverse Wave Crest Trough 8

amplitude The higher the amplitude, the more energy the wave is carrying In a longitudinal wave- it’s how tight the compressions are 9

Frequency & Wavelength Wavelength Distance between to identical points on adjacent waves. Meters As the wavelength decreases the frequency increases Frequency Number of waves per second Hertz 10 λ

Movement of a Transverse Wave 911 CLIP

Example - Water Remember: Energy is transferred ---- NOT THE MATTER!-- 12

Longitudinal Waves Longitudinal waves are a series of PUSHES & PULLS in which the motion of the medium is in the same direction as the wave Ex. Sound Waves 13

Characteristics of a Longitudinal (Compressional) Wave 14

Parts of a Longitudinal wave Compressions & Rarefactions Rarefaction is a place where the atmospheric pressure is lowest. 15

Speed of a wave ν = f λ ν is the velocity (m/s) f is the frequency (hertz) λ is the wavelength (m) The speed of a wave changes as it moves through different media The speed of a mechanical waves is constant for any given medium.. 16

Wave interactions with matter Reflection occurs when a wave hits another wave or object that it cannot pass through and bounces back. 17

18 Refraction Refraction occurs when a wave passes from one medium to another at an angle and bends (changes direction) due to a change in speed.

Diffraction is a wave phenomenon that is dependent on wavelength Light waves bend as they pass by the edge of a narrow aperture or slit Diffraction occurs when a wave passes through an opening and spreads out 19

20 Constructive Interference Constructive Interference occurs when two or more waves hit the same point and combine to produce a larger single wave. Destructive Interference Destructive Interference occurs when two or more waves hit the same point and combine to produce a smaller single wave.

Constructive Interference

Destructive Interference Clip