ESSENTIAL QUESTION-WHAT ARE SOUND WAVES AND LIGHT WAVES AND HOW DO THEY CARRY ENERGY DIFFERENTLY?

Waves pt 2Sound vs LightChapter 17 Chapter 19

Vocabulary

MediumLoudnessPitchIntensityColorDoppler Effect

ReflectionEchoEardrumFundamental Frequency

Reverberation

Review Vocabulary

WavelengthFrequencyMechanical WaveElectromagnetic Wave

Sound vs Light Waves

Sound waves are mechanical waves. They need matter to move and cannot move through empty space.

We cannot hear sounds in space. We have to send messages with radio waves that are transferred to sound by a speaker in the astronaut’s helmet or in a cabin with air.

Light waves are electromagnetic waves and can travel through empty space.

Example: We can see light from the sun and other heavenly bodies that are not in our atmosphere

SOUND MUST HAVE VIBRATION TO EXIST.

Vibration- the movement of molecules (air, water, or any other medium) that transfers sound waves.

Sound is caused by the vibration of a substance and is carried through the vibration of a medium.

If there is no medium (or matter) between the original vibration and our ears we cannot hear the sound because it will not be carried.

The Speed of Light vs the Speed of Sound

Light moves at 300,000,000 m/sec (much faster than sound)

We see the lightning first

Sound moves at 340 m/sec through air. (It moves faster through water.)

Then we hear the thunder seconds later (depending on how far away it is.)

Speed of SoundSpeed of Light

Sound Amplitude and Loudness

Loudness- a person’s understanding of how much energy a sound wave carries

Higher amplitude waves are louder

Light and Amplitude

When light has a higher amplitude it has a higher energy. We say it is more intense or brighter.

Frequency and Wavelength

The frequency is the number of waves that pass a point in space during any time interval, usually one second.

Waves with a longer wavelength will not pass a point as quickly as a waves with a shorter wavelengths.

Frequency and Pitch of Sound

Pitch-how high or low a note of sound is.

What is Music?

Noise- sounds with no planned organization

Music-a group of sounds put together on purpose to make a regular pattern.

Wavelength determines the color of light

How We See Color

Colored Light

White light is a combination of all

of the colors

A prism breaks color up by wavelength

Reflected Color(colored pigment)

We see the colors that are reflected back. All of the other colors are absorbed.

An object is white if it reflects all of the colors

An object is black if it absorbs all colors.

Color Mixing With Light And Pigment

Colors of Light Colors of Pigment

Reflections and Echoes

An Echo is a reflected sound wave.

A reflection of light is a “mirror image.

The Doppler Effect

The change in frequency of a sound wave when the source of a sound moves compared to the listener.

.Astronomers use the color shift of light

caused by the Doppler effect to record the movement of stars and other bodies in space.

The Doppler effect also works with other types of waves. Doppler Radar works by measuring the Doppler affect of radio waves bounced off of clouds