•                       Study  of Waves

What are the three different kinds of waves?

A.    Sound waves (compression waves are longitudinal waves)

B.    Light waves (transverse waves) make up part of the electromagnetic spectrum

C.    Seismic waves (primary waves – compression waves) and (secondary waves-transverse waves)

Definition to each part of a wave      8-27

1.      Rest position

A.     Middle position between crest and trough

2.     Crest

A.    It’s the very top of the wave

3.     Trough

A.     It’s the very bottom of the wave

4.    Wavelength

A.     It’s the distance from one crest to the next or from trough to next trough

5.     Amplitude

A.     It’s the distance from rest to crest or rest to trough

6.     Frequency

A.     It’s the number of waves that pass a point in one second

8-28

Q  What would a sound wave look like if it had a lot of energy?

Ans.  The wave would have a high amplitude.

Q  What would a sound wave look like if it had a high pitch?

Ans.  The wavelength would be short.

·       Waves transfer _______________  without transferring matter.  Ans.  Energy

·       Why does sound travel faster through a solid than a liquid or a gas?

Ans.  Molecules are closer together in a solid.

8-29

Q.  What causes a wave to occur?

Ans.  Initial energy input causes a wave, which transfers energy.

Q.   Is sound a wave a mechanical wave or an electromagnetic wave?  Explain

Ans.  Sound is a mechanical wave because it transfers energy through a medium, such a gas, liquid or solid.

9-2

Q.  What is the difference between a mechanical transverse wave and a mechanical longitudinal (sound) wave?  Explain

Ans.  A transverse wave displaces particles perpendicular to the direction of the wave.

Ans.  A longitudinal wave displaces particles parallel to the direction of the wave.

9-3      Waves with gummy bears

Q1.  What type of wave is this?

Ans.  Transverse wave

Q2.  What was the initial energy used to create a disturbance that went from one end of the wave to the other end?

Ans.  He moved one of the gummy bears and let go.

Q3.  Does the speed of the wave change?   What can change?

Ans.  No  Ans.  The amplitude and frequency

9-4

Q.  what are the four properties of waves?

Ans.  1)  amplitude

2)  wavelength

3)  frequency

4)  speed

9-8

EQ  What are the 3 types of seismic waves?

1)     Longitudinal wave, which is also called a P-wave- This wave is the fastest- It’s also called a compression wave and can go through solids and liquids

2)    The transverse wave – Also called the S-wave-This wave cannot go through liquids

3)    The last type of seismic wave is the surface wave – This wave causes the most damage- It’s the slowest wave- This wave is a combination of the other two waves

9-9  Seismic Waves

9-17

The following are the vocabulary words you need to know for Friday’s quiz over sound and waves:

1.     Wavelength     2.  Longitudinal wave  3.  Crest

4.  Transverse Wave   5. Energy   6.  Mechanical

1.     Trough      8.  Doppler Effect    9.  Amplitude

10.  Rarefraction  11.  Compression  12.  Wave  13.  Medium

14.  Vibration  15.  Seismic Waves  16.  Frequency

9-23  These notes go with the model of the ear.

How the ear works:  The outer ear funnels sound waves.  The middle ear transmits the waves inward and the inner ear converts the sound waves into a form that your brain can understand.

The following notes go with the numbered diagram on “How You Hear”.

1.     Ear canal-The ear canal directs sound waves toward the eardrum.

2.    Eardrum-Sound waves make the eardrum vibrate, which then causes the hammer to vibrate.

3.    Cochlea-when the liquid inside the cochlea moves, it causes the tiny hairs within it to move back and forth.  The hairs are attached to nerve cells that pass messages on to the brain.

4.    Outer ear-The outer ear collects sound waves and directs them toward the eardrum.

5.    Middle ear-The middle ear transmits vibrations from the eardrum to the cochlea.

6.    Inner ear-The inner ear converts vibrations caused by sound waves into messages your brain can understand.

9-29  Start of unit on the study of the electromagnetic spectrum and light

EQ:  What are electromagnetic waves?

They are transverse waves that have some electrical properties and some magnetic properties

Example:  Electric can be static, like what holds a balloon to a wall.

Magnetism can also be static like a refrigerator magnetic

When they come together they make waves such as electromagnetic waves

Draw a picture of an electromagnetic wave as seen on page O77

9-30

The Nature of Electromagnetic Waves

1.     What are the two kinds of fields that make up an electromagnetic wave?

Ans.  The two types of waves are electric and magnetic

2.     What is the speed of electromagnetic radiation in a vacuum?

Ans.  300,000 km/second

3.     How is the photoelectric effect evidence that light has some properties of a stream of particles?

Ans.  When a beam of light shines on some substances, it causes electrons in the substance to move.  If light did not have any of the properties of a stream of particles, this movement of electrons would not occur.

4.     How can two polarizing filters be used to show that light has some properties of a wave?

Ans.  A polarizing filter allows only waves of light that vibrate in one direction to pass through

Building Vocabulary

5.     The energy transferred by electromagnetic waves is called electromagnetic radiation.

6.     The photoelectric effect occurs when light causes electrons to move when it hits some substance.

7.    A photon is a particle of light energy

8.    Light that has passed through polarizing filters is polarized light.

9.    An electromagnetic wave consists of changing electric and magnetic fields.

10-8   Light and EM Waves Lab

T1  Experiment with mirrors – Explain what reflection is when using a mirror and flashlight

T2  Colors of Light with Cellophane and Colored Water – Explain  the additive process when adding colors of light together.

T3   Electromagnetic and UV Beads – Explain how an electromagnetic is related to the study of EM waves.  Write the colors of UV beads from lowest frequency to highest frequency.

T4  Colors with Spinners – Explain the subtractive process when adding pigment colors together.

T5   Experimenting with a Prism and Rainbow Glasses – Can you find Roy G. Biv?  Explain what the process is called to find Roy G. Biv.

T6  Light Energy to Create Movement – Explain how light energy is used to create movement.

10-13

EQ  What is the difference between opaque, transparent and translucent?

Opaque – You cannot see through opaque objects because light cannot pass through them

Transparent – When light strikes a transparent object, it passes right through, allowing you to see what is on the other side.

Translucent – You can usually tell that there is something behind a translucent object, but you cannot see details clearly.

10-14

EQ  What does it mean to have light refracted?

When light rays enter a new medium at an angle, the change in speed causes them to bend, or change direction.

EQ   What is the difference between colors of light and pigment colors?

When combining primary light colors (red, green and blue), the primary colors produce white light.  As pigment colors are added together, fewer colors of light are reflected and more are absorbed.

10-16

EQ  What are the similarities and differences between wavelike properties of energy in earthquakes, light and sound?

Earthquakes

-The wave transfers energy

-3 types of seismic waves

A.  P-wave – mechanical wave, fastest moving, longitudinal wave, can travel through solids and liquids

B.  S-wave – mechanical wave, second fastest, transverse wave, can only travel through solids

C.  L-wave or surface wave – combination of longitudinal and transverse, slowest moving, causes the most damage

Light Waves

-         The wave transfers energy

-         The wave is an electromagnetic wave (EM)

-         The wave travels at the speed of light

-         The wave is a transverse wave that can travel through empty space or a vacuum.

-         The greater the frequency, the greater the energy

-         Each color is denoted by a specific wavelength and frequency

-         The speed changes when traveling through matter.

-         Light can be refracted, diffused and absorbed.

-         Light can bounce off matter.

-         Light can be absorbed

Sound Waves

-         The wave transfers energy

-         The wave is a longitudinal wave

-         Travels slower than light

-         The greater the frequency, the greater the pitch

-         The intensity of the sound is measured in decibels

-         The greater the energy of the sound, the higher the amplitude

-         Sound can bounce off matter

-         Sound can be absorbed

-         Sound needs matter to travel through

-         Sound travels the fastest through solids, then liquids, then gasses

EQ:  How does the eye see?

Cornea:  transparent structure found in the very front of the eye that helps to focus incoming light.

Iris:  Located behind the cornea and it’s the colored ring-shaped membrane.  The iris has an adjustable circular opening called the pupil.

Pupil:  Allows a determined amount of light to enter.

Lens:  Located behind the pupil – a transparent structure that is convex.

Ciliary body (muscles) – These muscles surround the lens and hold the lens in place.  They are also responsible for helping the eye see objects for away and objects that are close.

Vitreous humor:  jelly – like tissue – After the lens, light travels through this humor before striking the sensitive layer of cells called the retina.

Three tissue layers that make up the eye – from outermost to innermost layer

A.     Sclera (gives eye its white color) and cornea

B.    Choroid:   Middle layer – contains blood vessels that supply the retina with nutrients and oxygen and removes its waste products.

C.    Retina:  Innermost layer – embedded are millions of light sensitive cells, which come in two main varieties:  rods and cones

Rods:  Helps you see objects when there is poor light, distinguishing among black and white.

Cones:  Helps you see color in bright light – 3 types of cones-detect red light, green light and blue light.

Optic nerve:  When light strikes either rods or cones of the retina, it’s converted into an electric signal that is relayed to the brain, which interprets this signal.