ESSENTIAL QUESTION - WHAT ARE SOUND WAVES AND LIGHT WAVES AND HOW DO THEY CARRY ENERGY DIFFERENTLY ? Waves pt 2 Sound vs Light Chapter 17 Chapter 19

Vocabulary Medium Loudness Pitch Intensity Color Doppler Effect Reflection Echo Eardrum Fundamental Frequency Reverberation

Review Vocabulary Wavelength Frequency Mechanical Wave Electromagnetic 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 Sound Speed 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 LightColors 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