Light Waves and Sound Waves

Waves: Light vs. Sound

Quick Review...

Multiple Choice

What is a disturbance that carries energy through matter?

• Wave

• Crest

• Trough

• Amplitude

Multiple Choice

Measuring the distance from crest to crest OR trough to trough describes...

• amplitude

• trough

• crest

• wavelength

Multiple Choice

The height of the wave from equilibrium to the crest describes...

• crest

• amplitude

• hertz

• equilibrium

Multiple Choice

Number of waves per second describes...

• trough

• wavelength

• frequency

• crest

Multiple Choice

Which wave in the diagram has the greatest frequency?

• 1

• 2

• 3

• 4

Multiple Choice

As the frequency of a wave increases, the ________ decreases.

• amplitude
• energy

• wavelength
• crest

Multiple Choice

The speed of the wave depends on its frequency and wavelength.

• True

• False

Multiple Choice

Both light and sound waves have an amplitude, wavelength, and frequency.

• True

• False

Mechanical Waves

Mechanical waves are carried by the oscillation of a medium.

A vibration at one point is transferred to the medium, and then across the medium through contact with neighboring molecules.
Individual molecules in the medium do not move very far, oscillating back and forth around their initial positions.

Video of Mechanical Wave

Multiple Select

Which of the following are mechanical waves?

• Radio Waves

• Sound Waves

• Seismic Waves

• Light Waves

Multiple Select

Mechanical waves can travel in...

• Solids

• Liquids

• Gases

• A Vacuum

Multiple Choice

The lowest frequency that we can hear is about 20 Hz. If the speed of sound in air is 340 m/s, what is the wavelength of that low sound?

• 0.059 m

• 17 m

• 170 m

• 6,800 m

Low frequency sounds are good at traveling a long way -- animals communicating a long way

​
High frequency sounds reveal more details when they bounce back -- animals using sonar

Detecting Sounds

Multiple Choice

As temperature increases, what happens to the speed of sound?

• Increases

• Decreases

• Increases, then decreases

• No Change

Multiple Choice

Is the speed of sound faster in saltwater or freshwater?

• Saltwater

• Freshwater

• They are the same

Multiple Choice

As rigidity increases, what happens to the speed of sound?

• Increases

• Decreases

• Increases, then decreases

• No change

Open Ended

How could you summarize these findings about what affects the speed of sound?

To summarize:

Anything that causes the molecules to collide more easily will increase the speed of sound

​The speed of waves increases as density increases

Electromagnetic Waves

A changing magnetic field will cause a changing electric field. These changing fields form electromagnetic waves.
Electromagnetic waves can travel outside of a medium, such as across the vacuum of space.
Different parts of the electromagnetic spectrum are transmitted well or poorly by different materials. Example: Earth's atmosphere can block UV radiation but transmits visible light.

Multiple Choice

All light waves have the same frequency.

• True

• False

Multiple Choice

Yellow light has a greater frequency than blue light.

• True

• False

Multiple Choice

Higher energy corresponds with...

• High frequencies

• Low frequencies

Reorder

Order the visible light from MOST energy to LEAST energy

• Violet

• Blue

• Green

• Yellow

• Red

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Open Ended

What kind of harm can these high energy forms of radiation cause?

Multiple Choice

All colors of light move at the same speed in a vacuum.

• True

• False

Multiple Choice

What is the speed of light in a vacuum?

• 8 x 10³ m/s

• 3 x 10⁸ m/s

• 5 x 10⁹ m/s

• 2 x 10² m/s

Multiple Choice

Light travels in a...

• Circular Path

• Straight Line

• Elliptical Path

• Rectangular Path

Wavelength in Different Media

When waves move from one medium to another, the frequency remains the same.

The wavelength changes as the wave speeds up or slows down.

Reorder

Order the media for shortest wavelength to longest wavelength for sound waves that pass through them.

• Air

• Water

• Glass

• Steel

1

2

3

4

• 1
• 2
• 3
• 4

Multiple Choice

What happens to an ultrasound wave that moves from blood to bone?

• The wavelength increases

• The frequency increases

• The wavelength decreases

• The frequency decreases