AIM:
How do we determine which factors affect the
period of a pendulum?
Do Now:
Draw a diagram of a pendulum and list what
you could change about it.
Homework
Finish lab!
Properties 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
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:
AIM:
What is a wave and how do we describe
them?
Do Now:
Draw a wave and label any part of the wave
you know.
Homework
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 spring
pendulum
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
T 
1
f
f 
1
T
Tf  1
Examples
1. 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 minute
a. What is the frequency of oscillation?
b. What is the period of oscillation?
Waves
• 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
The Electromagnetic Spectrum
• 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
VERY
wavelengths
VERYhigh
small
wavelengths
VERY
VERYhigh
low frequencies
frequencies
Visible Spectrum.
Each color is within
these FREQUENCY
ranges. Remember,
higher frequency,
lower wavelength
The Electromagnetic Spectrum
meters
Nanometers
Kilometers
Megahertz
Gigahertz
Two Classes of Waves
Transverse Waves
The particles vibrate in
a direction that is
perpendicular to the
waves propagation
(direction of travel)
Longitudinal Waves
The particles vibrate in a
direction that is parallel
to the waves
propagation
(aka compression waves)
Parts of a Wave
Crest: the top-most part of a wave
Wavelength (λ): the distance
Amplitude:
the
distance
from
the
between two similar points on a
equilibrium
line
to
the
crest
or
to
wave (measured in meters)
the trough (measure in meters)
Trough: the bottom-most part of a wave
Wave Pulse
One 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.
90o
One-quarter wavelength
180o
Half wavelength
Reference
Point
0o
360o
One full wavelength
270o
three-quarter 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
180o out
90o of
outphase,
of phase,
1/2 wave
1/4 wave
apartapart
o out of phase, AKA IN PHASE
o
360
270 out of phase, 3/4 wave apart
1 full wavelength apart
AIM:
What affects the speed of a wave?
How do we calculate a wave’s speed
Homework
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
Light 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
• 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
Recall…
• 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?
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
Antinodes:
Nodes: points
points that
that move
don’t the
move
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
wavelength
(m)
Time
for 20
(s)
Period
(s)
Frequency Speed
(Hz)
(m/s)
Large Amplitude
wavelength
(m)
Time
for 20
(s)
Period
(s)
Frequency Speed
(Hz)
(m/s)
• Data
Small Amplitude
wavelength
(m)
Time
for 20
(s)
Period
(s)
Frequency Speed
(Hz)
(m/s)
Large Amplitude
wavelength
(m)
Time
for 20
(s)
Period
(s)
Frequency Speed
(Hz)
(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 wave
1. 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 6MHz
a.
b.
c.
d.
What is the frequency in Hertz?
What is the speed of the wave?
What is the wavelength of the light?
What type of light wave is this?
Do Now
WORKING 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
AIM:
What is Reflection?
http://www.youtube.com/watch?v=kVzTWDwQzrc&feature=related
Do Now:
Describe what you heard and explain it in
terms of reflection
Homework
Castle Learning Assignment due Monday!
Wave
Behaviors
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
Law of Reflection
How to draw the diagram
• The Law of Reflection states
– Angle of incidence is equalNormal
to the angle
of reflection
Line:
A
Incidence Ray: The light ray on the way
INTO the surface
Angle of incidence ϴi:
angle made between the incident
ray and the normal line
reference line always
drawn perpendicular to
Reflected Ray: The light ray on
the
surface USE A
the way AWAY FROM the surface
PROTRACTOR!!!!
ϴi ϴr
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 Distance
Image Distance
Object
Eye sees
two
diverging
Normal Line
rays and
traces them
back
Image
Appears
where the
virtual
rays cross
Incident
Angle
Reflected
Angle
Mirror
Law of Reflection in a
PLANE mirror:
-Object distance (do) is
equal to image
distance (di)
Reflection Lab
Goals:
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 mirror
8. 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 Continued
2. 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
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 m
2. 3.0 × 10-2 m
3. 3.0 × 1010 m
4. 3.0 × 1018 m
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 of
1. regular reflection
2. diffuse reflection
3. reflected angles not being equal to incident angles
4. reflected angles not being equal to refracted angles
At the instant shown, a cork at point P on the water's surface is moving toward
A
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 wave
Rubens 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
Incident
Crest
Incident
Crest
Reflected
Trough
Reflected
Crest
fixed and free end reflection
Resonance
Resonance is…
When a small amount of
energy…
Added at the right
frequency…
Produces a large
amplitude…
resonance tuning forks
glass breaking 1
breaking glass 2
glass 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 sources
Point 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 tank
a way to show wave behaviors
•
•
•
•
•
•
•
Point source
Plane wave
Angled Reflection
Diffraction around a corner
Single slit
Double slit
Doppler effect
Point Source
Plane wave
Angled Reflection
Diffraction around a corner
Single Slit
Double slit
Doppler effect
Your own:
Aim: How do we recognize various wave behaviors?
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: What is refraction and how do we use it in every day
life?
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
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
n 
v
– 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!
AIM:
How do we apply Snell’s Law when finding the
index of refraction of a medium?
Remember, Snell’s Law:
n1 sin  1  n 2 sin  2
Do Now:
First page of packet (#6).
Homework
-Make sure lab is complete
- finish packet
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
Normal line
Incident rays.
15o increments
Refraction
Block
Top view
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
Requirements
1. 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
Flint glass
Air
• Using a ruler and protractor, find the refracted
angle for each incident angle. You can use colored
pencils to differentiate
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