131
Slide 1 / 131
Slide 3 / 131
Table of Contents
· What are Waves?Click on the topic to go to that section
· Sound
· Sight
· Color
· Digitized Information
· Describing Waves
· Mirrors
· Refraction
Slide 5 / 131
Where have you seen waves?
At the beach?
On a guitar?
At a baseball game?
Slide 6 / 131
What are Waves?
Each of these examples move up and down and across in a regular pattern (you never see just one wave at the beach).
Can you think of any other times you see something moving like that?
Slide 7 / 131
Water Waves
After dropping a rock or other object into the water basin you should have seen something like the image above.
We're now going to make some waves of our own.
Your teacher should have a basin filled with water.
Slide 8 / 131
Water WavesHere is a simulation of what we just saw.
Can you see the waves moving out from the lower left corner?
What started these waves moving?
Slide 9 / 131
Water WavesBefore the rock is dropped, the water is flat, calm, and not moving .
The scientific word for that is equilibrium.
Before we drop the rock, the water is in equilibrium.
Slide 10 / 131
Water Waves
The rock falls in the water, sinks, and pushes the water out of its way. This water goes up and over the surface and moves away
from the rock - this is a wave!
The water is no longer in equilibrium, it is disturbed. The waves move in a nice pattern, repeating themselves!
Slide 11 / 131
Rope WavesHere's a simulation (remember - it's a model that helps us
understand how the real thing works) of the waves that were created in the rope lab.
What disturbance created these waves?
The light blue curvy line is a picture of the rope. Each little dot is just one point on the rope.
Slide 12 / 131
Rope Waves
Look at any dot on this simulation.
Which way is that single dot moving? Right? Left? Up? Down?
Slide 13 / 131
Transverse WaveThe dot is moving up and down, as you can see in the simulation
below.
There is a special name for a wave where the individual dots move up and down. It's called a transverse wave.
If this were a water wave, the dots would be little drops of water. If it were a rope wave, the dots would be the pieces of the rope moving up
and down.
Slide 14 / 131
1 Waves are regular patterns of motion that are caused by a disturbance.
True
False
Slide 15 / 131
2 What kind of a disturbance will cause a water wave to start?
A Listening to the water.
B Dropping a rock into a basin of water.
C Looking at the water.
Slide 16 / 131
3 As you wiggle a rope, a transverse wave moves along the rope away from your hand. Which way does each piece of the rope move?
A Up and down.
B Outward from your hand
C Inward towards your hand
Slide 18 / 131
Describing Waves
Scientists like to name things - this helps them understand what is happening in the world and helps them invent new things.
There are a lot of different names for waves!
Slide 19 / 131
Describing Waves
Let's begin by drawing a dotted line going through the center of a transverse wave (remember, this is a wave where the disturbance is going up and down as the wave moves left or right).
Slide 20 / 131
Equilibrium
The dotted line actually means something. If you were looking at a lake with no waves on it, would it look like that dotted line?
What term did we learn which means when something is flat and calm?
Slide 21 / 131
Crest
All transverse waves have a crest.
How many crests does this wave have?
The crest is the highest point the wave reaches. Think of a crest like the
top of a hill.
Slide 22 / 131
Trough
The trough is the lowest point the wave reaches.
All transverse waves also have a trough.
How many troughs does this wave have?
Slide 23 / 131
Describing WavesCan you see that the wave goes above the dotted line (equilibrium) just as much as it goes below the line?
Using the terms that we just learned, can you see that the
________ and the _________ are equally far away from the
dotted line?
Slide 24 / 131
Amplitude
This distance from the dotted line (equilibrium) to the crest or the trough is called the amplitude of the wave.
What do you notice about these two distances?
Slide 25 / 131
4 What do we call the top part of a wave? This is the point where the wave is the furthest distance above the equilibrium line.
A Amplitude
B Crest
C Trough
Slide 26 / 131
5 What do we call the bottom part of a wave? This is the point where the wave is the furthest distance below the equilibrium line.
A Amplitude
B Crest
C Trough
Slide 27 / 131
6 When we measure the distance from the equilibrium line to the crest or the trough, what do we call it?
A Amplitude
B Crest
C Trough
Slide 28 / 131
Wavelength
Remember how we measured up and down in the wave and called it the amplitude?
What if we measured side to side?
Slide 29 / 131
7 Measuring a wave up and down gives wavelength, and measuring a wave side to side gives wavelength.
True
False
Slide 30 / 131
Time Behavior of WavesWe have been describing waves in terms of distances, but now
we are going to look at their timing.
Here we are only looking at the movement of the wave
from left to right.
Here we are looking at the individual pieces moving
up and down.
Do you see the difference?
Slide 31 / 131
This time is the period.
Period
Below is a diagram of a wave with two arrows. These arrows are appropriately one wavelength away from each other.
Using the timer to the right, determine how long it takes for the trough at the tip of the green arrow to hit the tip of the red arrow.
Slide 32 / 131
Period
The period is the time it takes for the wave to return to the same point.
It is the time it takes for the trough (the lowest point of the wave) at the tip of the green arrow to hit the red arrow.
Slide 33 / 131
Period
After the wave completes one period, it has moved a distance of one wavelength.
We just compared the time it takes for a wave to go somewhere (period) to the distance it traveled (wavelength)!
measuring time = periodmeasuring distance = wavelength
Slide 34 / 131
Frequency
Something else that is closely related to period is frequency.
You probably know what frequency is but just have not applied it to science before.
If you go to science class once per day, that is the frequency of your class.If you go to karate lessons twice per week, that is also a
frequency.
Frequency is the number of times something happens in a certain amount of time.
Slide 35 / 131
Frequency
Let's apply that idea to waves.
The frequency is the number of wavelengths that pass a point within a certain unit of time.
You just count the number of peaks (or troughs) that go by a point.
If 3 peaks go by in one second, then the frequency is 3 per second.
Slide 36 / 131
8 The distance between two crests of a wave that are next to each other is called:
A frequency
B amplitude
C wavelength
Slide 37 / 131
9 The distance between two troughs of a wave that are next to each other is called:
A frequency
B amplitude
C wavelength
Slide 38 / 131
10 The number of wavelengths that pass a point in a certain time is called:
A frequency
B amplitude
C wavelength
Slide 39 / 131
11 The part of the wave that doesn't go above or below the line, it stays on the line, is defined as:
A the crest
B the trough
C equilibrium
Slide 40 / 131
12 How many crests does this wave have?
Slide 41 / 131
13 How many troughs does this wave have?
Slide 42 / 131
14 Which wave has the largest wavelength?
A
B
C
Slide 43 / 131
15 Which wave has the smallest wavelength?
A
B
C
Slide 44 / 131
16 Which wave has the largest amplitude?
A
B
C
Slide 45 / 131
17 The crest is labeled _______.
A
B
C
D
E
Slide 46 / 131
18 The wavelength is labeled _______.
A
B
C
D
E
Slide 47 / 131
19 The equilibrium is labeled _______.
A
B
C
D
E
Slide 48 / 131
20 The trough is labeled _______.
A
B
C
D
E
Slide 49 / 131
21 The amplitude is labeled _______.
A
B
C
D
E
Slide 50 / 131
22 The time it takes to move one wavelength is known as the ___________.
A period
B frequency
C amplitude
D equilibrium time
Slide 51 / 131
23 The number of times a wave moves one wave length in a given unit of time is the _________.
A period
B frequency
C amplitude
D equilibrium time
Slide 52 / 131
Paper Wave LabWhen we measure side to side, we are looking at wavelength.
The wavelength is the distance until the wave repeats itself (remember that a wave repeats itself because it moves in a pattern). In this lab you will create a wave using a repeating
motion over a piece of paper.
It is the distance from a crest to the next closest crest.It is the distance from a trough to the next closest trough.
wavelength
wavelength
wavelength
Slide 54 / 131
SoundIf you move your hand back and forth quickly with the palm of
your hand facing your ear, do you hear something? (Make sure not to hit yourself!)
How did you make sound in this case?
Slide 55 / 131
Sound
By moving your hand back and forth you are pushing the air between your hand and your ear.
This movement creates a sound wave which will travel to your ear!
Some of the kinetic energy from your hand moving is changing into sound energy, which is carried by this sound wave.
Slide 56 / 131
Air
The air around you is occupied by very small objects that we call particles. You can't see them, because they're too small!
These particles collide with one another transmitting the sound waves.
You know the particles are there because you can see them if there is a haze.
Slide 57 / 131
SoundHere is a simulation of this motion. The little dots are the air particles.
The grey bar on the left side of the picture represents your hand pushing on the air. The sound wave then moves through the air through a series of collisions, until it reaches your ear where you
can hear the sound.
Animation courtesy of Dr. Dan Russell, Grad. Prog. Acoustics, Penn State
Slide 58 / 131
Sound
Describe the motion of the black dots in the picture above.
It might look like the vertical lines of black dots start on the left and go all the way to the right.
Animation courtesy of Dr. Dan Russell, Grad. Prog. Acoustics, Penn State
Slide 59 / 131
Sound
But now, just look closely at the red dots (this works for all the particles, however it's just easier to look at the red dots).
They're moving to the right, then the left! And they wind up in the same place. So the dots (air particles) don't move all the
way from the left to the right.
How is this different from the water waves?
Animation courtesy of Dr. Dan Russell, Grad. Prog. Acoustics, Penn State
Slide 60 / 131
Longitudinal Waves
The type of wave you are producing here is referred to as a longitudinal wave.
In a longitudinal wave, the particles move in the same or opposite direction as the wave. Longitudinal waves also happen in other
cases - not just sound waves.
An easy way to demonstrate this is to use a slinky.
Slide 61 / 131
Longitudinal Waves
In the image below, we have an already stretched out slinky (the left side was attached to a hook and the person pulled it all the way out
to the right). She then pushed and pulled on it.
This created a longitudinal wave as shown above.
Do you see the wave moving through the slinky?
Slide 62 / 131
Longitudinal Waves
With the sound wave in air, the air particles move back and forth as the wave travels.
Sound waves are longitudinal waves.
The motion of the coils in the slinky above are longitudinal waves. What's the same about sound longitudinal waves and slinky
longitudinal waves? What's different?
Slide 63 / 131
Longitudinal Waves
A longitudinal wave is made by hitting an object (making it vibrate) or by pushing back and forth on a material (like air or the slinky).
A longitudinal wave needs to move through some form of matter, and if there is nothing to push on then the wave cannot move.
What is the wave actually moving through in the slinky?
Slide 64 / 131
Sound
Remember that longitudinal waves need something to move through.
In science fiction movies, when a spaceship blows up in
space, it typically makes a very loud sound.
Can that actually happen?
Is there air in space?
Slide 65 / 131
24 A sound wave is an example of a ___________ wave.
A Transverse
B Longitudinal
Slide 66 / 131
25 A water wave is an example of a ___________ wave.
A Transverse
B Longitudinal
Slide 67 / 131
26 How would you make a longitudinal wave in a slinky?
A Move one end up and down.
B Move one end in a circle.
C Move one end back and forth (compressing the slinky).
D Do nothing to the slinky.
Slide 68 / 131
27 Where can sound not move?
A In metal
B In water
C In air
D In a vacuum
Slide 69 / 131
28 Why can't sound move in outer space?
A there is no matter for the sound to move through
B because it's a transverse wave
Slide 70 / 131
Sound Lab
Let's now take some time to explore sound using a cup and a string.
Slide 71 / 131
Sound
Sound waves are made by vibrating objects which then transfer energy.
Different things were vibrating in this experiment.
Can you name some of them?
Slide 72 / 131
Sound
Let's do another experiment on sound, but this time we're going to
make a 1-string guitar.
Remember sound is a type of energy that travels in waves and transfers energy from one point to another.
This time, instead of using our voice to start the waves, we're going to
pluck a string with our fingers.
Slide 73 / 131
Sound
When you pluck the guitar string you create a vibration in the string.
This vibration is similar to the string-cup lab.
What happened when you put the box next to the guitar string in the lab?
Slide 74 / 131
Sound
While playing with your one string guitar did you notice what happened as you move your hand down the guitar while plucking
the string? If not, give it a try now.
The sound didn't get louder but started to become higher pitched.
What does "pitch" mean?
Can you change the pitch of your own voice? Try it now.
Slide 75 / 131
Sound
Is a high pitch sound always louder then a low pitch sound?
Girls usually sing with a higher pitch than boys.
Does this mean they are always louder?
Slide 76 / 131
29 A deep sounding voice has a low pitch.
True
False
Slide 77 / 131
30 A high pitch can be louder than a low pitch.
True
False
Slide 78 / 131
31 A low pitch can be louder than a high pitch.
True
False
Slide 79 / 131
Summary of Types of WavesLabel the two types of waves below.
TransverseWave
LongitudinalWave
Slide 80 / 131
Summary of Types of Waves
Transverse wave: the particles in the wave move up and down while the wave moves right or left.
What type of waves did we say move like this?
Slide 81 / 131
Summary of Types of Waves
Longitudinal wave: moves by pushing stuff such as air, or from a vibrating object.
The waves made by pushing on a slinky (one that is already stretched out) are longitudinal waves.
What other type of waves did we say were longitudinal?
Slide 83 / 131
Sight
If we have all the lights turned off can you see anything?
If all the lights are on, can you see then?
So, why can you see things? What must you have in order to see?
Slide 84 / 131
Light
We can only see an object when light is present. Sources of light,
such as the sun or a lightbulb, give off rays of light.
Slide 85 / 131
Light
In years past in science, we learned these rays of light will continue to travel in straight paths until they collide with something.
The the light is either reflected, absorbed, or bent.
Slide 86 / 131
Sight
In order to see the box you need to have light rays striking its surface and being reflected.
Slide 87 / 131
Sight
When no light rays strike the surface there is nothing to be reflected towards your eye, therefore you cannot see.
nothing is reflected
Slide 88 / 131
32 In order to see we need ___________.
A the lights off
B the lights on
Slide 90 / 131
Color
So far we have covered what it means to see an object. You need light rays to strike an object and be reflected towards your eyes so you can see it.
But why do we see color? What makes one object
appear a different color then another?
Talk about this for a minute with a partner.
Slide 91 / 131
Color
The color of an object is determined by the light that is absorbed and reflected off its surface.
All of the colors are contained within a beam of white light, such as those from the sun or a light bulb.
Slide 92 / 131
Prism and a Rainbow
When we passed a beam of white light through a glass prism we saw the following colors:
Red, Orange, Yellow, Green, Blue, Indigo, and Violet
This is also how a rainbow is formed!
What does the light pass through when a rainbow occurs?
Slide 93 / 131
ColorThe colors that you see are a result of the absorption of certain colors and the reflection of others.
Reflected
The tree appears green because the rest of the colors are absorbed and only the color green is reflected to your eye.
Slide 94 / 131
33 What can be used to split white light into other colors?
A a rock
B a mirror
C a rainbow
D a prism
Slide 95 / 131
34 This square appears blue because:
A only the color blue is absorbed and the rest of the colors are reflected
B only the color blue is reflected and the rest of the colors are absorbed
Slide 96 / 131
35 If white light means having all the colors, what color do you see if everything is absorbed and nothing is reflected (hint - what do you see if there are no colors)?
A Yellow
B Black
C Blue
D Red
Slide 98 / 131
Plane Mirror Lab
When you look directly at a mirror you seen an image as if it appears on the other side. How far away is that image from the
mirror?
Slide 99 / 131
Light Reflection Lab
When a beam of light hits the surface of a mirror at an angle, at what angle
will it be reflected?
As you probably know, a mirror will reflect light.
Slide 100 / 131
36 In the diagram below, which path will the reflected beam take?
a
b
c
incoming ray
Slide 101 / 131
Reflection
The beam of light will be reflected along path b.
It leaves at the same angle that it hit the mirror's surface.
b
Slide 102 / 131
37 Where will the image appear when looking into the mirror? Position A, B, or C?
object
mirror
A B C
Slide 103 / 131
Reflection
The object will appear at position B, it will be as far back in the mirror as it is in front of it.
mirror
object B
Slide 104 / 131
Mirrors
How many different types of mirrors are there?
Have you noticed any of them in your daily lives? If so, where were they?
Slide 105 / 131
Mirrors
There are three different types of mirrors:
Plane Mirror Convex Mirror Concave Mirror
Slide 106 / 131
Plane Mirrors
A plane mirror has a flat reflective surface. It shows a normal sized image that isn't distorted.
An example would be a normal mirror on a wall
Slide 107 / 131
Convex Mirrors
A convex mirror has a bump in the reflective surface which reflects light over greater angles.
An example would be the mirrors on the side of a car.
Slide 108 / 131
Concave Mirrors
Concave Mirrors have an indent in the reflective surface, it causes light to focus more at one point.
An example would be the mirror in a flashlight.
Slide 109 / 131
Mirrors
This year, we are only going to talk about the plane mirror.
If you are interested in seeing what a concave and convex mirror do to an image, when you get home look at your reflection on both sides of a metal spoon.
Make sure you change how far away you are from the spoon. You may have to nearly touch one surface in order to see something cool happen!
Slide 110 / 131
Plane Mirror
A plane mirror can be used simply to look at yourself while you are brushing your or doing your hair. Since a plane mirror does not change the way you look in the mirror, it is the best thing to look at.
Also, remember that a plane mirror reflects light at the same angle it reaches the mirror. Look at the examples below to see this.
Slide 111 / 131
Slide 112 / 131
Slide 114 / 131
RefractionAs we mentioned before, light rays can be reflected, absorbed,
and also bent.
Have you ever put a straw or pencil in a glass of water? Did anything seem odd?
If we were to put the ruler into the water what would we see?
Slide 115 / 131
Refraction
When the ruler is place in the water it seems to have bent, so what is happening here?
Does the ruler actually bend when being placed in the water?
Slide 116 / 131
Refraction
The ruler is just fine. It hasn't changed. Instead, we are looking at refraction, or the bending of light.
The light coming from beneath the water is being bent in such a way that it appears as if something happened to the ruler.
Slide 117 / 131
Light bends as it passes from one material to another. Passing through water as well as other materials into air results in the bending of the light rays.
Refraction
Objects that use refraction include magnifying glasses and binoculars!
Slide 119 / 131
Communications
When we want to talk to family or friends, we are able to simply pick up a phone, dial a number, and speak into it.
Communicating was not always like that.
In ancient times the means of communicating were as basic as writing a letter and giving it to someone who would run great distances to deliver the message.
Slide 120 / 131
Communications
Can you come up with other ways people could have communicated over large distances a long time ago?
We have talked about this in science before.
Drumming is one example.
Slide 121 / 131
Communications
In today's day and age information can now be transmitted through waves.
There are many devices that allow
you to communicate today.
Can you name others?
Slide 122 / 131
Digitized Information
Many devices utilize waves in order to transmit information. For example, when you talk into the microphone on a cellphone it registers the sound waves coming from your mouth. It is then turned into an electrical signal and transmitted to another phone where it is converted back into sound waves.
A similar process takes place in a radio.
Slide 123 / 131
Digitized Information
Just as we communicate through different languages, whether it is English, Spanish, French and so many others, computers also have their own language known as Binary. Instead of words, computers communicate through a list of 1's and 0's, by turning different parts inside the computer on and off.
Did you realize your cellphone, video game boxes, PCs, and tablets are all different types of computers?
Slide 124 / 131
Digitized Information
Let's say we give you a set of numbers (100010001, for example), and told you to put them into a 3x3 grid as if your were writing on a piece of paper.
Then let's say that the number 1 in each box means its a black square and any box that contains a 0 is white.
The image would look like the following:
1 0 00 1 00 0 1
Slide 125 / 131
Digitized InformationIf we give you a set of numbers:
000000000010101110010100100011100100010100100010101110000000000 and told you to put them into a 7x9 grid as if your were writing on a piece of paper, what would the image read?
Slide 126 / 131
Digitized Information
This means of sharing information is rather simple.
Another nice example is Morse Code. Morse code is comprised of a series of either short and long signals.
Using Morse Code, you can communicate with one of your friends simply by taping on a table or flashing a light in a certain combination.
For example:
If you flashed the light quickly three times, then three times slowly, and then again three times quickly, you would have sent
out the message SOS, a distress signal.
Slide 127 / 131
Digitized Information
Slide 128 / 131
Slide 129 / 131
39 The language of computers that works using zeros and ones is called __________.
A Morse Code
B Binary
C Coding
D Os and 1s
Slide 130 / 131
40 Cellphones use waves to communicate.
True
False
Slide 131 / 131
Binary Code Lab0 0 0 0 0 0 0 0 0
0 1 0 1 0 1 1 1 0
0 1 0 1 0 0 1 0 0
0 1 1 1 0 0 1 0 0
0 1 0 1 0 0 1 0 0
0 1 0 1 0 1 1 1 0
0 0 0 0 0 0 0 0 0
Teac
her N
otes
