Textbook Assignment #1: DUE Friday 5/9/2014 Read: PP Do Review Questions Pg 388 # 1-20

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2 Page 2 of 38 Unit Packet Contents Unit Objectives Notes 1: Waves Introduction Guided Practice: Waves Introduction (CD pp 89-90) Independent Practice: Speed of Waves Notes 2: Interference and Diffraction Concept Development: Wave Superposition (CD pp93 94) Guided Practice: Doppler Effect Notes 3: Reflection / Refraction Independent Practice: Snell s Law Notes 4: Wave Phenomena Textbook Assignment #1: DUE Friday 5/9/2014 Read: PP Do Review Questions Pg 388 # 1-20 Textbook Assignment #2: DUE Tuesday 5/13/2014 Read PP Do Review Questions PG 401 #1-20

3 Page 3 of 38 Name Date Notes: Waves Intro Regents Physics Objectives: 1. Define the terms periodic wave, wave motion, transverse wave, longitudinal wave, and surface wave, and provide examples of each. 2. Compare and contrast mechanical waves with electromagnetic waves. 3. Define the terms period, frequency, amplitude, and wavelength, and solve problems that relate these quantities to wave speed. Vibrations A vibration is considered to be a in time. A vibration cannot exist in one but must move back and forth during a period of Systems that vibrate: Pendulum wiggle instant o - A swinging bob at the end of a string. time spring o Mass on the end of a Pulses and Waves energy. mass single disturbance Wave -- being transferred through a medium without the net movement of Pulse -- A of a medium that is not repeating Periodic Wave -- (Wave train) A disturbance of a medium that a regular interval energy Waves transfer... When the wave reaches the duck the duck moves but not so... matter... waves do not transfer up and down repeats in forward

4 Page 4 of 38 Wave Description Motion of a pendulum or a weight bouncing on a spring is known as motion Simple harmonic motion is motion that in a particular way. Simple harmonic motion includes and can be described by several characteristics. How to describe a wave oscillates wave motion simple harmonic crest node nodal line Wavelength -- The distance from a point on a wave to the on the next wave Amplitude -- The distance from the nodal line to the of a wave. Frequency -- The number of times the in a given second of time. Units waves/second = which is the same thing as Period The amount of time required for one. Speed of a wave T o The at which the disturbance of the medium is traveling. o Speed of a wave is related to the wavelength and the frequency by the formula: 1 f v f same point crest or trough medium is disturbed hertz 1/s or s -1 time rate complete oscillation T = period (seconds) f = frequency v = speed of wave = wavelength f = frequency trough

5 Page 5 of 38 Example 1: What is the frequency in vibrations per second of a 60-Hz wave? What is its period?

6 Page 6 of 38 Types of Waves 1. Transverse Waves A transverse wave is a wave that oscillates in a direction that is to the direction of the motion of the wave itself. On the following waves label: 1. direction of wave travel 2. direction of medium displacement Examples of transverse waves are: ocean waves, guitar string, light waves perpendicular 2. Longitudinal Waves A longitudinal wave is one where the medium oscillates in a direction the direction of overall wave motion. parallel to

7 Page 7 of 38 Name Regents Physics Date Independent Practice: Speed of Waves

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9 Page 9 of 38 Name Regents Physics Date Interference Notes: Interference and Diffraction Wave Phase Wave is used to compare on different waves. phase On the following wave points A and B are, points B and C are completely out of phase 2 points in phase and points C and D are. A B partially in phase Superposition principle Or Combining Waves C D same medium When two or more waves pass through the, the displacement at any point in the sum of displacements medium is the by each wave, 1. Waves that are in phase and have the same frequency.

10 Page 10 of Waves out of phase, same frequency

11 Page 11 of Waves w/ different frequency Beats When two waves with very interfere they produce a new wave with alternating high and low amplitudes. High amplitude is heard as and low amplitude as low volume. Sounds like Diffraction Bending The of waves around a corner Example: hearing sound waves when the sources is, Laser light bending around a hair. similar frequencies high volume WA WA WA wa WA WA - WA Opening for waves should be only slightly larger than the of waves passing through. around a corner The pattern in the diagram represents wave and troughs or bright and dark wave fronts. crests wavelength screen hair laser light rays hy6zsd0 8a61G8Hvi0

12 Page 12 of 38 Double slit experiment When a wave pattern is passed through 2 adjacent slits, diffraction occurs at each slit. Alternating constructive and destructive interference results in a projected dark light and pattern on a screen.

13 Page 13 of 38 Doppler Effect Occurs when a wave producing source and an observer are in motion relative to one another. In diagram A above the source of sound is Observer A and B both hear the same frequency as the frequency that is equal Note the wavelength is at all points surrounding the source In diagram B above the source of sound is moving to at constant speed. Higher frequency stationary Observer C hears a than the source is emitting. The wavelength of sound waves the observer C hears is lower frequency the left shorter Observer D hears a than the source is emitting. longer emitted The wavelength of sound waves the observer D hears is

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15 Page 15 of 38 Guided Practice: Doppler Effect

16 Page 16 of 38 TTQ s: Wave Properties, Interference, Diffraction

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21 Page 21 of 38 Name Date Regents Physics Notes: Reflection/Refraction Objectives: 1. Define wavefronts and use rays to represent wave motion. 2. Explain reflection and state the law of reflection. 3. Explain refraction and use Snell s law to predict the path of a refracted wave. 4. Explain wave diffraction. Wave Motion: Fronts same phase Wave fronts are portions of a wave in which particles are all in the of motion. Rays -- A that shows the direction of a wave s motionreflection Reflection of a wave pulse When a wave strikes a surface it of the surface changing its path of motion The reflected pulse has the medium displaced in the compared to the incident pulse. line or arrow bounces off According to Newton s 3 rd law, when a force is exerted on an object, the object exerts an equal force in the opposite direction. opposite direction The rope exerts a force on the brick wall so the brick wall exerts a force on the rope in the opposite direciton.

22 Page 22 of 38 Incident angle Not all lines are normal A normal line is a line drawn the reflecting surface at the point of the reflected ray Incident angle -- The angle between the and the incident ray perpendicular to normal line and the reflected angle is for the reflected wave Law of reflection -- Angle of incidence is equal to angle of reflection. Refraction i r Imagine a marching band marching across a and then onto a grass field. Each marcher individually will march in the grass than on the pavement. Consider each line of marchers to simulate a for a wave. If the marchers march onto the grass at a to the interface between the pavement and the grass. o Lines of marchers will become slow down as marchers in front before marchers in back. o The band as a whole change direction. If the marchers march onto the grass at an angle. less than 90. will not paved parking lot slower wave front 90 angle θi = angle of incidence θr = angle of reflection closer together

23 Page 23 of 38 slows down change direction o One end of each line before the other end. o The band as a whole will When a wave traveling through a medium strikes the to a new medium the ray splits into One part is of the boundary and continues to travel through the first medium two parts reflected off of o On the diagram below draw the reflected ray on the Crown glass surface. The other part is transmitted into the new medium and as it enters the different medium, the speed of the wave changes which causes the wave to. o On the diagram below draw the ray that is transmitted into the Crown Glass frequency The of the wave depends on the wave source which does not change. o The frequency of the wave in the Crown Glass is the frequency of the wave in Air. If the speed of the wave changes and since v= f than the must also change To describe this process we define the following normal line o A is an imaginary line drawn at the point where the ray meets the boundary and perpendicular to the boundary. angle that the incident refracted o The ray makes with the normal is the angle of incidence o The angle the makes with the normal is the angle of refraction. boundary change direction the same as wavelength Label the diagram with Incident ray Incident angle θi Not θi Normal Medium interface Refracted ray Not θr Refracted angle Reflected ray Reflected angle θr incident light ray reflected ray Not θi θi θr Not θr Air medium interface normal Crown Glass refracted ray

24 Page 24 of 38 Snell s Law Relates the to the ray for waves passing from one medium to another. Absolute index of refraction: Index of refraction is characteristic of. Describes refraction of. Ratio of speed of light to speed of light in the. n n n 2 1 c v v v incident ray in a vacuum refracted the material light waves n = absolute index of refraction c = speed of light in a vacuum v = speed of light in the medium (characteristic of medium) OR n1sin 1 n2sin 2 If a light ray passes from a medium with lower refractive index to higher n1 < n2 slows down towards o The light ray in the new medium. o The ray bends in a direction the normal. If a light ray passes from a medium with higher refractive index to lower. n1 > n2 travels faster away from o The light ray in the new medium. o The ray bends in a direction the normal. - See REFERENCE TABLES medium Air Crown Glass Water

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29 Page 29 of 38 Name Regents Physics Date Independent Practice: Refraction and Snell s Law

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31 Page 31 of 38 Name Date Regents Physics Notes: Wave Categories and Phenomena Objectives: 1. Explain the difference between mechanical waves and electromagnetic waves. 2. Define electromagnetic energy and discuss the parts of the electromagnetic spectrum. 3. Define the term polarization, and explain why polarization distinguishes between transverse and longitudinal waves. Mechanical vs. Electromagnetic waves Mechanical waves -- medium of matter neighboring particles Need to travel through a like air, water etc. Displaced particles displace as wave is propagated through the medium Sound Waves are an example of mechanical waves Speed of sound in air at STP is Types of waves are consisting of and rarefactions 331 m/s longitudinal waves existing in air molecules. compressions Electromagnetic waves -- rarefaction compression electric and magnetic fields perpendicular to Energy flow is changing Electric field and magnetic field traveling with waves each other.

32 Page 32 of 38 Examples: light, microwaves, ultraviolet, infrared, x-rays, gamma rays. higher energy higher frequency lower wavelength lower energy lower frequency higher wavelength Speed of light All electromagnetic waves have the in a vacuum which is 3x 10 8 m/s See reference tables slower same speed Light travels in a material medium and its speed depends on the medium. decreases Since speed is constant and v = f, as frequency of light increases, wavelength Sample Problem 1: Find the wavelength of a red light photon that has a frequency of 4.05 x Hz. Sample Problem 2: What is the frequency of a microwave that has a wavelength of 8.95 x 10-2 m? Resonance Every flexible body has a particular frequency called its By exerting a periodic force on a body at its natural resonance frequency, the body will at this frequency and we say that resonance is occurring. If the rate of the periodic force does not match the resonance frequency than resonance occur. Resonance examples: Tacoma narrows bridge 1940 Opera singer shatters wine glass with voice natural resonance frequency oscillate will not

33 Page 33 of 38 Polarization of light Imagine a beam of light pointed at an eye all directions Normal light rays consist of electromagnetic fields vibrating in. A polarizing filter can remove all light rays except for those vibrating in one direction Two polarizing filters together can block out of light rays. Regular Reflection vs. Diffuse Reflection nearly 100% Regular reflection mirrors Polished surfaces like produce regular reflection parallel Reflected rays are Diffuse reflection Irregular surfaces, paper page etc. all angles Reflected rays emerge at.

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35 Page 35 of 38 TTQ s Set 2: Reflection / Refraction

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