Do Now Grab a notecard and select TWO topics from this unit that you are not confident in. On one side, write everything you know about one topic. On the other side, write everything you know about the other topic. Get any make-up work from last week now!

Do Now Important Dates Quiz Overview Round 7 Unit Review Today’s Agenda 5 min Do Now Important Dates Quiz Overview 45 min Round 7 Unit Review

Do Now Important Dates Quiz Overview Round 7 Unit Review Today’s Agenda 5 min Do Now Important Dates Quiz Overview 45 min Round 7 Unit Review

Important Dates and Reminders Last Unit Exam on Thursday Practice Test Due Wednesday Worth double points on homework! Tutoring This Week Today and Wednesday from 4 – 5 PM Missing or Zero-Grade Assignments Check TeacherEase for what’s missing Prom Tickets On Sale Today in Lunch

Do Now Important Dates Quiz Overview Round 7 Unit Review Today’s Agenda 5 min Do Now Important Dates Quiz Overview 45 min Round 7 Unit Review

Problem 1 Identify the angle of incidence or the angle of reflection (depended on what version quiz you had)

Problem 2 Which of the following describes the difference between reflection and refraction? Reflection is when light bounces off a surface and refraction is when it bends at the boundary between two surfaces. Refraction is when light bounces off a surface and reflection is when it bends at the boundary between two surfaces. Reflection depends on the medium and refraction depends on the angle of incidence. Reflection depends on the angle of refraction and refraction depends on the medium

Problem 3 Diamond has a greater index of refraction than plastic. Based off of this, which of the following is true regarding diamond vs. plastic? Diamond is lighter than plastic. Diamond is heavier than plastic. It is easier for light to travel through diamond rather than plastic. It is harder for light to travel through diamond rather than plastic.

Problem 4 An incident ray in air (n=1.0) strikes an unknown material at an angle of 58°. The angle of refraction is 42°. What is the index of refraction (n) of the unknown material?

Problem 5 An incident ray in water (n=1.33) is approaching the boundary with glass (n=1.52) at an angle of incidence of 35°. Calculate the angle of refraction.

Do Now Important Dates Quiz Overview Round 7 Unit Review Today’s Agenda 5 min Do Now Important Dates Quiz Overview 45 min Round 7 Unit Review

Unit Exam Topics Wave Basics Wave Anatomy Frequency & Period Speed of a Wave Electromagnetic Spectrum Reflection & Refraction Snell’s Law Critical Angle

Wave Basics A wave is a repeating vibrating disturbance that travels through space or another material. Examples of waves are sound, light and water. Pulse is just a single disturbance. Waves transfer energy from one place to another with no transfer of matter.

Wave Types Transverse Longitudinal Particles vibrate perpendicularly to the direction the wave energy is traveling Particles vibrate parallel (back and forth) to the path the wave energy is traveling http://www.youtube.com/watch?v=7cDAYFTXq3E http://www.youtube.com/watch?v=Rbuhdo0AZDU

Wave Types: Part Two Electromagnetic Mechanical Wave that is capable of transmitting its energy through empty space Example: Light Wave that is NOT capable of transmitting its energy through empty space  must have matter to transfer Examples: Water, Sound Both transverse and longitudinal waves are MECHANICAL! http://www.physicsclassroom.com/mmedia/waves/em.cfm http://teachertube.com/viewVideo.php?video_id=202143

Check for Understanding Sound needs a medium to travel through. When it travels, it’s particles move back and forth. What two types of wave could you describe sound as? Mechanical Electromagnetic Transverse Longitudinal

Crests & Troughs Crests: maximum upward displacement (highest point) Troughs: maximum downward displacement (lowest point)

Wavelength wavelength ___________________ (λ): the distance between identical parts of the wave (measured in meters) – easiest way to measure is from crest to crest OR trough to trough

Amplitude amplitude ___________________ (A): the maximum distance of a wave upward from the center (measured in meters). This represents the energy carried by a wave.

Amplitude & Energy A wave with larger amplitude carries more energy than a wave with a smaller amplitude.

Label The Wave Label the crests, troughs, amplitude and wavelength on this blank wave.

Longitudinal Waves Compressions: maximum density, individual particles pressed close together Rarefactions: minimum density, individual particles spread apart

Frequency (f) Frequency (ƒ) is how often a vibration occurs OR how often the particles of the medium vibrate when a wave passes through the medium Frequency is a rate. The unit of frequency is the Hertz (Hz) This stands for “per second” or 1/s or s-1

Frequency & Wavelength Big wavelengths have low frequencies. Small wavelengths have high frequencies.

Period (T) A period (T) is how long or the time required to complete a single cycle Examples in Real Life It takes the Earth 365 days to complete a cycle Our class period cycle is 60 minutes. The period for the minute hand on a clock is 60 minutes. The unit for a period is seconds (s).

Frequency vs. Period How often a vibration occurs How long it takes to complete a single cycle

Frequency vs. Period Practice A swing has a period of 8 seconds. What is its frequency? A wave has a frequency of 5 Hz. What is its period?

Frequency vs. Period Practice A swing has a period of 8 seconds. What is its frequency? F = 1/8 = 0.1 Hz A wave has a frequency of 5 Hz. What is its period? T = 1/5 = 0.2 s

Speed of a Wave

Check For Understanding The speed of a wave depends upon: The properties of the medium through which the wave travels The wavelength of the wave The frequency of the wave Both the wavelength and the frequency of the wave

Calculating Wave Speed The “wave equation” is: Where v = ________________________ ƒ = ________________________ λ = ________________________ V = ƒ *λ Wave speed or velocity in m/s Frequency in Hz Wavelength in meters (m)

Speed of a Wave Practice 1 A certain ocean wave has a frequency of 0.5 Hz and a wavelength of 20 meters. What is the wave’s speed? V = ƒ *λ

Speed of a Wave Practice 1 A certain ocean wave has a frequency of 0.5 Hz and a wavelength of 20 meters. What is the wave’s speed? V = (0.5 Hz)(20 m) V = 10 m/s V = ƒ *λ

Speed of a Wave Practice 2 What is the wavelength of a sound wave with a frequency of 550 Hz if the speed of sound is 344 m/s? V = ƒ *λ

Speed of a Wave Practice 2 What is the wavelength of a sound wave with a frequency of 550 Hz if the speed of sound is 344 m/s? 344 m/s = (550 Hz)*λ λ= 0.63 m V = ƒ *λ

Speed of a Wave Practice 3 What is the frequency of a wave that is traveling at 15 m/s if its wavelength is 0.38 m? V = ƒ *λ

Speed of a Wave Practice 3 What is the frequency of a wave that is traveling at 15 m/s if its wavelength is 0.38 m? 15 m/s = f(0.38 m) F = 39.5 Hz V = ƒ *λ

Check for Understanding Which region of the electromagnetic spectrum has the shortest wavelength? Radio

Check for Understanding Which region of the electromagnetic spectrum has the longest wavelength? Radio

Visible Light Spectrum Visible light spectrum is the very narrow band of wavelengths located in between the infrared region and ultraviolet region. Electromagnetic waves are a wide range of wavelengths but our eyes are only sensitive to this  The wavelengths range from 400 nm to 700 nm. Acronym Fun: ROYGBIV

Check for Understanding Which color of the visible light spectrum has the longest wavelength? Red

Check for Understanding Which color of the visible light spectrum has the shortest wavelength? Red

Reflection Describes how light bounces off of a surface

Law of Reflection The normal is a line perpendicular to the surface It is at the point where the incident ray strikes the surface The incident ray makes an angle of θ1 with the normal The reflected ray makes an angle of θ1’ with the normal θ1=θ1’

Refraction Describes how light bends at the boundary between two media

Refraction of Light The incident ray, the reflected ray, the refracted ray, and the normal all lie on the same plane The angle of refraction, θ2, depends on the properties of the medium

Index of Refraction The index affects the angle that light will bend at which shows that the speed of light is changing in different media

Where n is the index of refraction SNELL’S LAW Where n is the index of refraction

Review Problem 1 An incident ray in water (n=1.33) strikes an unknown material at an angle of 65°. The angle of refraction is 40°. What is the index of refraction (n) of the unknown material?

Review Problem 1 Answer An incident ray in water (n=1.33) strikes an unknown material at an angle of 65°. The angle of refraction is 40°. What is the index of refraction (n) of the unknown material? (1.33)sin(65) = n2sin(40) N2 = 1.9

Review Problem 2 An incident ray in air (n=1.0) is approaching the boundary with glass (n=1.50) at an angle of incidence of 57°. Calculate the angle of refraction.

Review Problem 2 Answer An incident ray in air (n=1.0) is approaching the boundary with glass (n=1.50) at an angle of incidence of 57°. Calculate the angle of refraction. (1.0)sin(57) = (1.50)sin(θ2) θ2 = 34

Review Problem 3 An incident ray in glass (n=1.50) is approaching the boundary with diamond (n=2.52). If the angle of refraction was 35°, calculate what the angle of incidence was. Think-Pair-Share

Review Problem 3 Answer An incident ray in glass (n=1.50) is approaching the boundary with diamond (n=2.52). If the angle of refraction was 35°, calculate what the angle of incidence was. (1.50)sinθ1 = (2.52)sin(35) θ1 = 74.5 Think-Pair-Share

Total Internal Reflection Total internal reflection happens when light tries to go from a medium with a higher index of refraction to one with a lower index of refraction Ray 5 shows internal reflection

Total Internal Reflection For this to occur, your angle of incidence would have to be greater than something called the critical angle

Critical Angle A particular angle of incidence will give you an angle of refraction of 90° This angle of incidence is called the critical angle

Solving Critical Angle Problems The light has to be moving from the medium with a larger index of refraction to the medium of a smaller index of refraction. Calculate the critical angle at the boundary for water (n=1.33) and plastic (n=1.75). Remember: Your angle of refraction is 90 degrees! You always go from higher n to lower n!

Solving Critical Angle Problems The light has to be moving from the medium with a larger index of refraction to the medium of a smaller index of refraction. Calculate the critical angle at the boundary for water (n=1.33) and plastic (n=1.75). (1.75)sinθ1 = (1.33)sin(90) θ1 = 49.5

Big Questions Any questions from the material that we have reviewed that should be addressed whole group?

Practice Test You have the last few minutes to work independently on your practice test. You should only be using notes as a last resort and when using notes, only use them as a GUIDE. Remember that when you take the exam, you will have no notes so you should practice for the exam in the same way.