What do all these pictures have in Common?

Chapter One, Section One Waves Chapter One, Section One

Waves Carry Energy Waves are rhythmic disturbances that carry energy without carrying matter.

A model for waves Think about the ripples made when you jump into water. The energy carried by the ripples travels through the water. The water molecules that make up the water pass the energy

A model for waves The water molecules transport the energy in a water wave by colliding with the molecules around them.

Mechanical Waves The types of waves that use matter to transfer energy are called Mechanical Waves The matter through which a mechanical wave travels is called a medium. Examples Students passing the object Water moving the energy

Mechanical Energy Why do the astronauts have microphones?

Mechanical Energy A mechanical wave travels as energy is transferred from one particle to another in the medium. Examples: Sound wave is a mechanical wave that can travel through the air as well as solids and liquids. Without the medium for energy to travel through you would not hear sound.

Mechanical Waves Mechanical Waves Transverse Waves Compressional Waves

Transverse Waves In a mechanical transverse wave, the wave energy causes the matter in the medium to move up and down or back and forth at right angles to the direction of the wave.

Transverse Wave As the energy moves through a transverse wave the matter does not move. The waves have peaks and valleys at regular intervals. High points of the wave = crests Low points of the wave = troughs

Transverse wave

Compressional Waves In a compressional wave, matter in the medium moves forward and backwards in the same direction that the wave travels. A compressional wave is also known as a longitudinal wave .

Compressional Waves Compressional waves carry only energy forward along the spring. The area in which the wave is squeezed together is called compression The area in which the wave is stretched apart is called rarefaction

Compressional Waves

Sound Waves Sound waves are compressional waves Examples of sound waves: Talking Music coming out of the speaker Drums What do these examples have in common? All waves are produced by something that is vibrating.

Making Sound Waves How do vibrating objects make sounds waves? Drum Example: When you hit the drum it starts vibrating up and down. As the drumhead moves upward the molecules next to it are pushed closer together - compression When the drumhead moves downward, the molecules have more room to spread farther apart – rarefaction This series of compressions and rarefactions is called a sound wave.

Making Sound Waves

Chapter one, section two Wave properties Chapter one, section two

Amplitude How high or low the wave rises or falls below the normal level is called the wave’s amplitude. The amplitude is ½ the distance between the crest and the trough In compressional waves, the amplitude is greater when the particles of the medium are squeezed closer together in the compression.

Amplitude

Amplitude and energy A wave’s amplitude is related to the amount of energy that it carries with it. Example: Electromagnetic waves that make up bright light have greater amplitudes than the waves that make up dim light.

Amplitude and Energy Sound waves Greater amplitude = more energy Loud sounds = greater amplitude= more energy Soft sounds= lower amplitude = less energy Greater amplitude = more energy Lower amplitudes = less energy

Wavelength For a transverse wave – wavelength is the distance from the top of one crest to the top of the next crest or the bottom of one trough to the bottom of the next trough. For a compressional wave= wavelength is the distance between the centers of one compression to the center of the next compression, or the center of one rarefaction to the center of the next rarefaction.

Wavelength Electromagnetic waves that range from kilometers to no less the diameter of an atom.

Frequency Frequency of a wave is the number of wavelengths that pass a given point in one second The unit of frequency is the number of wavelengths per second or hertz. The faster the vibration is, the higher the frequency of the wave that is produced.

Frequency and wavelength Longer wavelength lower frequency Short wavelength Higher frequency This is true for all waves that travel at the same speed

Color and pitch The frequency and wavelength determine the color of visible light.

Color and pitch In sound waves, either the wavelength or frequency determines the pitch. The pitch is the highness or lowness of a sound.

Wave Speed Mechanical waves (compressional and transverse) and electromagnetic waves move at different speeds through different materials.

Wave Speed Mechanical Waves Mechanical waves travel faster in a medium in which atoms are closer together. Which types of materials do mechanical waves travel best: Solids Liquids gases

Wave Speed Electromagnetic Waves Unlike mechanical waves, electromagnetic waves travel faster in a medium in which atoms are more spread out or not present. Which types of materials do electromagnetic waves travel best: Open space(no matter) Gas Liquids Solids

Chapter one, Section Three Wave Behavior Chapter one, Section Three

Type of wave behaviors Reflection Refraction Absorption

Reflection Reflection occurs when a wave strikes a shiny object or surface and bounces off. An echo is reflected sound.

Reflection An echo bounces off walls, ceiling, furniture, and people. A reflection occurs when light waves bounce smooth, shinny surface. Smooth surface = clear and sharp image Uneven surface = unclear image ;l

Reflection When light hits a smooth shiny surface, it is reflected at the same angle that it comes in. Angle of incidence is the angle at which light strikes an object. Angle of reflection is the angle at which light is reflected off an object.

Angle of incidence = Angle of reflection

Refraction The bending of a wave as it moved from one medium to another is called refraction. Refraction occurs when the speed of the wave changes as it passes from one substance to another.

Refraction and wave speed A line that is perpendicular to the surface of the object is called the normal. The larger the change in speed is the larger the change in direction.

Colors from refraction Refraction causes prisms to separate sunlight into many different colors and produce rainbows

Absorption of light When you shine light through a prism it a appears as a rainbow because white light is a mixture of all the colors that make up visible light.

Why do objects have color? Why does grass look green or a rose looks red? when a mixture of light waves strike an object that is not transparent, the object absorbs some of the light waves. If an object looks red, it absorbs all the other colors of the spectrum and reflects red. If the object appears black, it absorbs all the colors of the spectrum.

The Nature of Electromagnetic Waves Chapter three, Section one

Electromagnetic waves Transferring Energy A wave transfer energy from one place to another without transferring energy The sun is 92,960,000 miles away. How do the sun’s rays get to Earth if there is no matter to travel through? Electromagnetic waves

Transferring energy An electromagnetic wave is a wave that can travel through empty space and is produced by charged particles that are in motion.

Forces and Fields An electromagnetic wave is made of two parts: An electric field A magnetic field

electromagnetic waves An electromagnetic wave is made of electric and magnetic fields. Electromagnetic waves are produced by making charged particles, such as electrons, move back and forth causing them to vibrate.

Electromagnetic waves A charged particle always is surrounded by an electric field.

Electromagnetic Waves A charged particle that is in motion is also surrounded by a magnetic field.

How the waves are created A charged particle vibrates by moving up and down or back and forth It produces changing electric and magnetic fields that move away from the vibrating charge in many directions. These changing fields traveling in many directions from an electromagnetic wave.

Wavelength and frequency When the charge makes one complete vibration, one wavelength is created. The frequency of an electromagnetic wave is the number of wavelengths that pass by a point in one second.

Radiant energy The energy carried by the electromagnetic wave is called radiant energy What happens if an electromagnetic wave strikes another charged particles? The electric field of the wave exerts a force on the particle causing it to move

The Electromagnetic Spectrum The wide range of electromagnetic waves with different frequencies and wave lengths is called the electromagnetic spectrum.

The Electromagnetic spectrum All the waves in the electromagnetic spectrum are produced by electric charges that are moving or vibrating. The faster charges vibrate, the higher the energy of the electromagnetic wave. http://www.brainpop.com/science/energy/electromagneticspectrum/

The Electromagnetic spectrum Electromagnetic waves carry radiant energy that increases as the frequency increase

The difference between analog and digital signals

Analog vs. Digital

Analog vs. digital Analog and digital signals are used to transmit information, usually through electric signals. In both these technologies, the information, such as any audio or video, is transformed into electric signals

Analog vs. digital In analog technology, information is translated into electric pulses of varying amplitude. In digital technology, translation of information is into binary format (zero or one) where each bit is representative of two distinct amplitudes.

Analog Vs. digital Analog Digital Technology - The analog sound wave replicates the original sound wave Data Transmission – noise interference when sending signals Examples – human voice, analog electric devices Memory - Stored in the form of wave signal Technology - Samples analog waveforms into a limited set of numbers and records them. Data Transmission- No interference when sending signals Examples- Computers, CDs, DVDs, and other digital electronic devices. Memory- Stored in the form of binary bit

Analog vs. Digital

Analog vs. Digital

Advantages of digital signals Signals do not get interference Digital signals typically use less bandwidth. This is just another way to say you can cram more information (audio, video) into the same space. Digital can be encrypted so that only the intended receiver can decode it ( secure telephone etc.)

What are some ways that you talk to your friends?

Telecommunications

Digital ways of communication There are three primary ways in which information is shared digitally: Radio waves Fiber optic cables

Using Radio Waves Radio waves are used to send and receive information over long distances. Advantages of radio waves: Pass through walls easily Do not interact with humans Not harmful to humans

Using Radio waves Objects that use radio waves to send information: Cell phones Blue tooth Computers iPads Radio GPS ……plus many more

Using fiber optics Fiber optics works by sending information coded in a beam of light down a glass or plastic pipe A fiber-optic cable is made up of 100 or more incredibly thin strands of glass or plastic known as optical fibers.

Using fiber optics Fiber-optic cables carry information between two places using entirely optical (light-based) technology. Hook your computer up to a laser, which would convert electrical information from the computer into a series of light pulses. Fire the laser down the fiber-optic cable. After traveling down the cable at the speed of light, the light beams would emerge at the other end. A photoelectric cell (light-detecting component) then turns the pulses of light back into electrical information his or her computer could understand.

Using fiber optics https://www.youtube.com/watch?v=9VmA2S2XiCo Advantages of fiber optics High capacity – transmits a lot more information Less signal degradation Uses less power Uses light signals-means clearer transmission