HomeworkFinish lab!

Do Now:Draw a diagram of a pendulum and list what

you could change about it.

AIM:How do we determine which factors affect the

period of a pendulum?

• What are three things you can change about an pendulum?– – –

• What would be the period of a pendulum?• How could you test if each of these factors affect

the period of a pendulum?• http://www.youtube.com/watch?v=r2gnD5NEplY

Properties of a Pendulum

Lab Goal: which factors affect the period of a pendulum?

• Groups 1, 2:– Does mass affect the period of a pendulum?

• Groups 3, 4:– Does length affect the period of a pendulum?

• Groups 5, 6, 7:– Does release height affect the period f a

pendulum?

Lab Write-up• Goals (all 3)• Background:

– What is a pendulum?– What is period?

• Predictions:– Which of the factors will effect the period of a pendulum?

• Procedures:– Mass– Length– Initial height

• Data/Analysis:• Conclusion:

Homework

Do Now:Draw a wave and label any part of the wave

you know.

AIM:What is a wave and how do we describe

them?

Blue book pg 153-155 #1-47

Simple Harmonic Oscillators• An object in simple harmonic motion experiences a

net force which obeys Hooke’s Law• The oscillator oscillates about an equilibrium

position (or mean position) between two extreme positions of maximum displacement in a periodic manner– Periodic means regular (same every time) and repeating

Mass on a springpendulum

Parameters and

parts of

waves

Vocabulary• Period (T):

– The time for one oscillation– Measured in Seconds– Period = Time/number of oscillations

• Frequency (f)– The number of oscillations in one second– Measured in Hertz; Hz (1/s or s-1)– Frequency = Number of oscillations/time

• Mathematical Relationship between Period and Frequency– Period and frequency are inversely related

1 1

1

TfT

ff

T

Examples1. A mass on a spring completes 10 oscillations in 30

seconds.a. What is the period of oscillation?b. What is the frequency of oscillation?

2. A pendulum completes 5 swings in a minutea. What is the frequency of oscillation?b. What is the period of oscillation?

• Waves are repetitive disturbances that transfer ENERGY without transferring MATTER – energy transferred without matter being transfered

• Mechanical Waves require a medium to travel through.• Mediums include; water, air, anything solid• SOUND is a mechanical wave • "the wave"

• Electromagnetic Waves do not require a medium to travel through. They can travel through a vacuum (empty space)

• Empty space exists outside of Earth’s atmosphere• LIGHT, Xrays, Radio Waves are all examples of electromagnetic

waves• electromagnetic waves

Waves

• ALL electromagnetic waves travel at the speed of light!– c is the symbol for the constant “speed of light”– c is always equal to 3x108 m/s when electromagnetic

waves are traveling through a vacuum.• This speed can be decreased by sending light through a

different medium• Nothing can ever travel faster than the speed of light.• Visible light is the same type of wave as a radio wave, an Xray,

or a microwave. Its just a different size!• electromagnetic spectrum

The Electromagnetic Spectrum

The Electromagnetic Spectrum

VERY small wavelengths

VERY high frequencies

VERY high wavelengths

VERY low frequencies

Visible Spectrum. Each color is within these FREQUENCY ranges. Remember, higher frequency, lower wavelength

The Electromagnetic Spectrum

Nanometers Kilometers

Megahertz

meters

Gigahertz

Two Classes of WavesTransverse Waves

The particles vibrate in a direction that is perpendicular to the waves propagation (direction of travel)

Longitudinal WavesThe particles vibrate in a

direction that is parallel to the waves propagation

(aka compression waves)

Parts of a WaveCrest: the top-most part of a wave

Trough: the bottom-most part of a wave

Amplitude: the distance from the equilibrium line to the crest or to the trough (measure in meters)

Wavelength (λ): the distance between two similar points on a

wave (measured in meters)

Wave PulseOne single Vibration or disturbance- The amplitude of SOUND ONLY tells you about the energy in the wave

• Transverse Pulse • Longitudinal Pulse

One Crest Or

One Trough

One rarefaction Or

One compression

Phase• The relative position between…

– Two different points on the same wave• Phase is measured in degrees and follows the

conventions of a sine curve.

Reference Point

0o

90o

One-quarter wavelength

180o

Half wavelength

270o

three-quarter wavelength

360o

One full wavelength

Phase• The relative position between…

– Two similar points on different waves• Pick the same point on each wave and look at the difference

between their relative positions

90o out of phase, 1/4 wave apart180o out of phase, 1/2 wave apart270o out of phase, 3/4 wave apart360o out of phase, AKA IN PHASE

1 full wavelength apart

Homework

AIM:What affects the speed of a wave?

How do we calculate a wave’s speed

Finish 1-47 in the blue book.

Questions are posted on the website

QUIZ ON THEM TOMORROW!

Do NOW!Make a compare and contrast list of

everything you know about sound waves and light waves

Sound Waves vs. Light Waves

Sound Waves

• Mechanical Wave• Longitudinal wave• Amplitude tells you about

volume• Frequency tells you about pitch• The speed of sound in air is

about 330m/s• Sound travels faster in most

solids than it does in air

Light Waves

• Electromagnetic wave• Transverse wave• Amplitude tells you about

intensity/brightness• Frequency tells you about type

of wave/color• The speed of light in air is

3x108m/s• Light slows down in solids

• You are standing on a dock and observe 15 waves pass you in 1 minute.– What is the frequency of the waves?– What is the period of the wave?

• What is the difference between a mechanical and electromagnetic wave?

• What is the difference between a transverse and longitudinal wave?

Recall…

standing wave• A wave that appears to be “standing still” and not moving either

left or right.- Particles seem to vibrate up and down

• In order to create a standing wave, you need- Two waves, moving in opposite directions, with the same

amplitude and frequency

Nodes: points that don’t moveAntinodes: points that move the most

Measuring Parameters of a Wave

• Goal: we are going to use a standing wave to measure and investigate the affect of the amplitude, frequency, period, and wavelength on the speed of a transverse wave.

• Prediction: Which of the four parameters do you think will affect the speed of the wave and why.

• Background: in a paragraph, please define all bolded words above.

• Diagram: Draw a diagram of a transverse wave and label all the parts of the wave.

• Materials– Slinky, stopwatch, meter stick

• Procedure– Measure 4m length across the floor and a 0.5m and 1m

amplitude.– Have one person hold one end of the slinky still while having

the other person generate a half wavelength standing wave with a 0.5m amplitude

– Have 10 classmates time 20 complete oscillations of the wave.– Calculate the period, frequency and wave length for this trail

and enter the numbers into the data table.– Repeat for a 1m amplitude then for 1 wave, 1.5 waves, 2

waves, 2.5 waves and possibly 3 waves.– Using the data table, try to determine how you would calculate

the speed of the wave.– Once the speed for each wave is calculated, determine which

parameters affect the speed of the wave and which don’t.

• Data

Small Amplitude Large Amplitude

wave-length

(m)

Time for 20

(s)

Period(s)

Frequency (Hz)

Speed (m/s)

wave-length

(m)

Time for 20

(s)

Period (s)

Frequency (Hz)

Speed (m/s)

• Data

Small Amplitude Large Amplitude

wave-length

(m)

Time for 20

(s)

Period(s)

Frequency (Hz)

Speed (m/s)

wave-length

(m)

Time for 20

(s)

Period (s)

Frequency (Hz)

Speed (m/s)

• Analysis– Show a sample calculation for each of the following

• Period of the wave• Frequency of the wave• Speed of the wave.

– What formula did you come up with to calculate this? (hint: use the units!)

• Percent difference between velocities.– Do they appear different?

• Conclusion– Restate goal– What is the formula for the speed of the wave?– What parameters affect the speed, which don’t?

• If the frequency was changed, did the speed or the wavelength change?

– How could you change the speed of this wave?– Sources of error/one future experiment

Calculating the speed of a wave1. A 5m long wave passes the end of a dock once

every 10 seconds.a. What is the period of the wave?b. What is the speed of the wave?

2. A light wave has a frequency of 6MHza. What is the frequency in Hertz?b. What is the speed of the wave?c. What is the wavelength of the light?d. What type of light wave is this?

Do NowWORKING ON YOUR OWN,

complete the crossword. You can use your notes. You have 7 minutes from the beginning of the period.

If you finish, take out the lab we worked on yesterday and finish writing the background and write a conclusion paragraph

• Conclusion– Restate goal– What is the formula for the speed of the wave?– What parameters affect the speed, which don’t?

• If the frequency was changed, did the speed or the wavelength change?– How could you change the speed of this wave?– Sources of error/one future experiment

HomeworkCastle Learning Assignment due Monday!

Do Now:Describe what you heard and explain it in

terms of reflection

AIM:What is Reflection?

http://www.youtube.com/watch?v=kVzTWDwQzrc&feature=related

Wave Behavior

s

3 Options• When a wave hits a

boundary, it does a combination of 3 things– Reflection

• Bounces off the boundary

– Absorption • Gets absorbed and turned

into heat

– Transmission• Goes through the

boundary

The transm

ission of the lights

on the inside of the building

The reflection of the lights coming off the car on the outside of the building

Law of ReflectionHow to draw the diagram

• The Law of Reflection states– Angle of incidence is equal to the angle of reflection

ϴi ϴr

Normal Line: A reference line always drawn perpendicular to the surface USE A PROTRACTOR!!!!

Angle of incidence ϴi: angle made between the incident ray and the normal line

Incidence Ray: The light ray on the way INTO the surface

Reflected Ray: The light ray on the way AWAY FROM the surface

Angle of Reflection ϴr: angle made between the reflected ray and the normal line

Reflection of Light• The bouncing of a wave off of a surface .

– Regular reflection• Bouncing off of a Smooth surface

– Mirrors, ponds– You can see an image of the object

– Diffuse Reflection• Bouncing off of a Rough surface

– The road, leaves, furniture, cloths– You can see light, but no image

Reflection of sound• The bouncing of a wave off of a surface.

– Regular reflection• Bouncing off of a Smooth surface• ECHOs

If the speed of sound in water is 1.5Km/s and the signal takes 0.8 seconds to come back to the boat, HOW DEEP IS THE WATER?

Echos A person in the grand canyon screams and hears

the sound come back to her 1.2 seconds later. How far away is the other face of the canyon?

Reflection Ray Diagram

Object

Mirror

Normal Line

Incident Rays

Incident Angle

Reflected Ray

Reflected Angle

Eye sees two diverging rays and traces them back

ImageAppears

where the virtual

rays cross

Object Distance Image Distance

Law of Reflection in a PLANE mirror:- Object distance (do)

is equal to image distance (di)

Reflection LabGoals:1. To draw a 2-ray diagram of a single pin image

a. Use this diagram to compare the incident angles to the reflected angle

- Use percent difference to determine if the object distance is the same as the image distance

b. Use this diagram to compare image distance to object distance

- Use percent difference to determine if the object distance is the same as the image distance

1. Draw a line down the middle of the page, perpendicular to the edge of the page

2. Prop the mirror up against the book with the BACK surface of the mirror on your mirror line. Make sure

the cardboard is under the paper

3. Stick the pin in the middle of the page

4. Look in the mirror from the angle and locate the image of the pin in the mirror

Image of the pin

5. Line up the edge of the ruler such that if extended into the mirror, it would run straight into the pin. Trace that line

6. Repeat step 5 from the other side

7. Extend the reflected rays back to the mirror8. Draw a line connecting the object to the place on

the mirror where the reflected rays hit

9. Trace the VIRTUAL rays back behind the mirror. The image appears where the rays meet

10. Use a protractor to construct the normal perpendicular to the mirror at the point where the rays hit the mirror.

11. Measure both incident and reflected rays and compare them using a percent difference

12. Label and measure the object distance and the image distance. Using percent difference, compare

these two numbers

Goals Continued2. To draw a 2-ray diagram of a single pin image

a. Use this diagram to compare the incident angles to the reflected angle

- Use percent difference to determine if the object distance is the same as the image distance

b. Use this diagram to compare image size to object size

- Measure the length of each side of the image and the object.

- Use percent difference to determine if the object distance is the same as the image distance

When light rays from an object are incident upon an opaque, rough-textured surface, no reflected image of the object can be seen. This phenomenon occurs because of1. regular reflection2. diffuse reflection 3. reflected angles not being equal to incident angles 4. reflected angles not being equal to refracted angles

A typical microwave oven produces radiation at a frequency of 1.0 × 1010 hertz. What is the wavelength of this microwave radiation?1. 3.0 × 10-1 m2. 3.0 × 10-2 m3. 3.0 × 1010 m4. 3.0 × 1018 m

At the instant shown, a cork at point P on the water's surface is moving towardA B C D

Electromagnetic radiation would be classified as 1. a torsional wave 2. a longitudinal wave 3. a transverse wave 4. an elliptical wave

Standing Waves Revisited

Do Now:- What are the three conditions that need to be

met to produce a standing wave?

- An example of a standing sound waveRubens flame tube

HW MAKE A REVIEW SHEET

Sound as Music- What is the relationship between frequency and

pitch?- Think of a trombone, how does the pitch of the

sound change as the length of the slide increases?- Based on this, how is frequency related to

wavelength?• blue man group

– What do you notice about the length of the tubes and the pitch of the waves? Does this confirm your statement above?

Reflection Continued• Fixed end Reflection

– 180o phase change• Free end Reflection

– No phase change

fixed and free end reflection

Incident Crest

Reflected Trough

Incident Crest

Reflected Crest

ResonanceResonance is…When a small amount of energy…

Added at the right frequency…

Produces a large amplitude…

resonance tuning forksglass breaking 1breaking glass 2glass music

Questions on the videos

• Video 1– What type of wave would be produced in the ping pong balls when hit with the paddle?

– What characteristic of sound does the frequency tell you about?

– When is one tuning fork able to resonate with another? When doesn’t it work?

– How does your radio work?

• Video 2/3– why is the sound of the glass considered resonance?

– What happened to the frequency when he added water?

– What would happen to the sound wave’s wavelength when the water was added?

– What would happen to the glass if he changed the frequency of the sound generator?

• Video 4– What do you notice about the pitches of the sound and the size of the glasses?

– Can you come up with an explanation of the relationship you wrote above?

• Include wavelength and frequency in your explanation

Two types of wave sourcesPoint Source

• One point that oscillates– Like a child bobbing in the

pool.– Produce circular waves

Plane Source• An extended (rectangular)

source that oscillates.– Produce plane waves

Diffraction• Diffraction is the bending of

a wave around a barrier– Consider a door cracked

open, what shape does the light make?

• If it didn’t bend, it would be a straight column

• As you can see the light ‘fans out’ after it passes through the barrier

Ripple tanka way to show wave behaviors

• Point source• Plane wave• Angled Reflection• Diffraction around a corner• Single slit• Double slit• Doppler effect

Point Source

Angled Reflection

Plane wave

Diffraction around a corner

Single Slit

Doppler effect

Double slit

Your own:

DO NOW:1. Which wave phenomena is exemplified by this picture?

2. As the wave propagates, explain what happens to the…

- speed of the wave

- the wavelength of the wave

- the frequency of the wave

- the amplitude of the wave

HW: Castle Learning on Diffraction-Due tomorrow. Counts as a 10pt HW assignment

Aim: How do we recognize various wave behaviors?

DO NOW:1. Name two different media

in this picture.2. What happens to light as it

passes from one medium to the other?

3. Offer an explanation as to WHY you are seeing what you see.

HW: Blue Book Review for test- all of waves up to diffraction: pg

Aim: What is refraction and how do we use it in every day life?

Refraction• Refraction is the BENDING of a wave as is travels

from one medium to another.• Remember: a wave changes speed when it moves

from one medium to another.

Index of Refraction• The index of refraction is similar to the coefficient of

friction.– It tells you how easily (quickly) light travels through a

substance– It has no units– The symbol for index of refraction is n– The formula for the index of refraction is

– c is the speed of light in a vacuum (3x108m/s)– v is the speed of light in the other medium.– The index of refraction is ALWAYS GREATER THAN ONE!

v

cn

Homework- Make sure lab is complete

- finish packet

Do Now:First page of packet (#6).

AIM:How do we apply Snell’s Law when finding the

index of refraction of a medium?Remember, Snell’s Law:

2211 sinsin nn

Using the Index of Refraction

1. In which medium does light move the fastest?

2. In which medium does light move the slowest?

3. In which two mediums will light have the same speed?

4. What is the speed of light in water?

Procedure:

1. Trace the block on a sheet of paper

2. Remove the block and construct a normal line close to the upper right hand corner

3. Using colored pencils, construct 5 incident rays at various angles between 15o and 60o

4. Replace the block, and using a ruler like the mirror lab, sight one of the incident rays through the block such that the ruler’s edge would run straight with the ray. Trace that ray and repeat for all 5 rays

5. Remove the block and connect the rays of the same color

6. measure the angle of refraction for each incident ray at the top of the block

7. Construct normal lines at each exit point and measure the incident and refracted angles.

8. Enter all angles in the data table

9. Graph sin θ1 vs. sinθ2 (what will the slope of this graph be?)

Do Now!

Finding the Index of Refraction

Goals: The goals of this lab include

to determine the index of refraction of the unknown block using a graph

Background

write a PARAGRAPH explaining how refraction works and what happens to all the parameters (speed, wavelength, frequency) of a light wave as it moves from one medium to another.

Procedure

based on the do now graph, what do we need to do to determine the index of refraction of a block?

Finding the Index of Refraction

Refraction Block

Top view

Incident rays.

15o increments

Normal line

Just like in the mirror lab, you will use a ruler to line up the ray while looking

THROUGH the block. You line of sight needs to be at table level! You can use

pins to help you line it up. Focus on ONE color at a time

Lab Requirements1. Each person needs

- A goal statement- Background PARAGRAPH on refraction and how it

works- A procedure- Well organized data table (similar to the do now)- Graph- Slop calculation and percent error- Conclusion PARAGRAPH

Do Now• Light is incident on a flint glass air boundary. The

light enters the air at the following angles– 10o – 20o – 30o – 40o

• Using a ruler and protractor, find the refracted angle for each incident angle. You can use colored pencils to differentiate

Flint glassAir

Dispersion

Polarization

Superposition

Constructive Interference

Destructive Interference

Double Slit Interference

Light as a wave

Light as a Particle

Wave Particle Duality

Energy of a Photon

Conservation of Mass/Energy