Ride the Wave Understanding different types of wave
Good, good, good, good vibrations! http://www.youtube.com/watch?v=NwrKKbaClME
Waves are created when a source of energy (force) causes a __________. • So what are vibrations? • A vibration is a repeated ________ and _________ motion or ____ and _____ motion.
Waves transfer energy not matter. The water waves below are carrying energy but are not moving. Waves can only exist as they have energy to carry.
Waves can be classified by WHAT they move through or by HOW energy moves through them.
There are two classifications forwavesbased on what theymove through: • Mechanical Waves • Electromagnetic Waves
Mechanical wavesare wavesthat can ONLY movethrougha medium(through matter).
Mechanical wavesrequiretheparticlesofthemediumtovibratein order for energytobetransferred.
water waves • earthquake/seismic waves • sound waves • waves that travel down a rope or spring All of these examplesCANNOT move through empty space.
Empty spaceis space in which NO MATTERis present. Another name for this is a vacuum.
A wave moving through a medium travels at a certain speed. This is Wave Speed. Wave speed is usually measured in meters/second, but may be measured using other distance units (such as centimeters per second).
Electromagnetic wavesarewavesthat can travel through matteror empty spacewhere matterisnot present.
radio waves • microwaves • infrared waves • visible light • ultraviolet rays • X-rays
There are two classifications for wavesbased on how energy moves through them: • Longitudinal Waves • Transverse Waves
Mechanical wavesin which the particlesof matterin the mediumvibratebypushing togetherandmoving apartparallelto the directionin which the wave travels are called longitudinal waves.
Compressional/ Longitudinal Wave On a compressional wave the area squeezed together is called the compression. The areas spread out are called the rarefaction. The wavelength is the distance from the center of one compression to the center of the next compression.
The place on the wavethat is pushed togetheris called thecompression and the place that is moving apartis the rarefaction.
sound waves • some waves in a spring • some seismic waves (earthquake waves- primary waves, to be exact)
What is sound? Sound is a compressional wave which travels through the air through a series of compressions and rarefactions.
Sound travels through different media. We hear sound which usually travels through air. Sound travels through other media as well, such as water and various solids. Sound travels different speeds in different media. Sound typically travels faster in a solid that a liquid and faster in a liquid than a gas. The denser the medium, the faster sound will travel. The higher the temperature, the faster the particles of the medium will move and the faster the particles will carry the sound.
Mechanical wavesin which the particlesofmatterin the mediumvibrateby moving back and forth and perpendicular(at right angles) to the direction the wave travels are called transverse waves.
The highest pointof a transverse waveis the crestand the lowest pointis called a trough.
What is wavelength? Wavelength is a measure of distance, so the units for wavelength are always distance units, such as meter, centimeters, millimeters, etc. What is wave frequency? Frequency is the number of waves that pass through a point in one second. The unit for frequency is waves per second or Hertz (Hz). One Hz = One wave per second. Wavelength and frequency are inversely related. The smaller the wavelength, the more times it will pass through a point in one second. The larger the wavelength, the fewer times it will pass through a point in one second.
The amplitude of a transverse wave is determined by the height of the crest or depth of the trough
strings on a musical instrument (not the sound) • waves on a rope • some waves in a spring • some seismic waves (earthquake waves- secondary waves, to be exact)
What are Seismic Waves? An energy wave which vibrates through the earth’s crust as the crust bends or breaks. Seismic waves exist as both transverse and longitudinal waves. Some travel through the earth and some travel across the earth’s surface.
Electromagnetic waves aretransverse wavesthatcan travel without a mediumthrough empty space. Examples: Radio Waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma Rays
Properties of Light Light is an example of a transverse wave.
Visible Light WavesWaves with a length of between 0.4 and 0.7 micrometers can be detected by the human eye. For these reason we call these waves visible light. As you look around the room everything you see has these waves bouncing off of them. If they didn’t, you would not be able to see them. What your eyes pickup and turn into a picture in your brain, are these visible light waves
Light travels VERY FAST – around 300,000 kilometres per second. • per second. At this speed it can go around the world 8 times in one second.
Thunder and lightning start at the same time, but we will see the lightning first. • Light travels much faster than sound. For example: • 2) When a starting pistol is fired we see the smoke first and then hear the bang.