 # We are beginning a new unit: Waves, Light, & Sound Introductory Video.

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We are beginning a new unit: Waves, Light, & Sound Introductory Video

Today we will be introduced to waves. The next two days we will try a new method of learning. We will perform a variety of experiments learning about waves BEFORE we read about them.

What are waves? The Sweet Wave

WAVES Carries energy from one place to another Classified by what they move through 1. Mechanical Waves the energy is transferred by vibrations of medium (medium = matter) ex/ ocean waves move through water 2.Electromagnetic waves (EM Waves) the energy moves through disturbances in the electromagnetic field. a disturbance that transfers energy

WAVE STRUCTURE CREST (peak) AMPLITUDE resting to max peak WAVELENGTH TROUGH

Basic Properties of Waves Amplitude Wavelength Frequency Hertz

AMPLITUDE The maximum distance the medium vibrates from the rest position Gives indication of “power” or “strength” of wave (magnitude of earthquake = Richter scale) Does not affect velocity of wave Determines loudness (sound) or brightness (EM wave)

Which has a larger amplitude?

WAVELENGTH Distance between any two corresponding parts of a wave crest-crest, trough-trough, expansion-expansion, compression- compression Determines what colors we see; what notes we hear (pitch) Shorter wavelengths have more cycles per minute because they aren’t as long

Which has a shorter wavelength?

Frequency The number of waves that pass a given point in a certain amount of time. AKA number of vibrations per second. Frequency measured in hertz (Hz).

Which has a higher frequency?

SPEED the rate at which the energy travels; speed & direction Depends on medium Mechanical waves travel faster through dense mediums EM Waves are faster through less dense mediums

MECHANICAL WAVES travel through & gradually lose energy to that medium Examples: water, sound, rope, & spring waves Mechanical Media: water, air, rope, spring require a medium ( the material through which the disturbance is moving) to transmit energy Making a pulse

MECHANICAL WAVES Classified by how medium vibrates Pulse = direction of energy transfer Vibration = direction of vibration of medium relative to pulse 3 typestypes: Longitudinal,transverse,surface

MECHANICAL WAVES Classified by how medium vibrates Longitudinal Waves: Vibration is in the same direction as wave pulse (parallel to wave pulse) Transverse Waves: Vibration is at 90 0 (right angles) to wave pulse Surface Waves: Vibration is circular Ex/ Ocean waves; surface waves

TRANVERSE WAVES Sideways or up & down Examples: S-type earthquake waves Electromagnetic (EM) or light waves Vibration is perpendicular to the direction of the motion of the wave

LONGITUDINAL WAVES Back and forth (compression & rarefraction) Also called compression or pressure wave Examples: P-type earthquake waves Sound waves Vibration is parallel to the direction of the motion of the wave Rarefraction (expansion) Compression

Compressional Wave Matter vibrates in the same direction as the wave travels. Example: Slinky

Compressional wave The parts,where the coils are close together are called compressions, the parts where the coils are spread out are called rarefactions.

Combinations of waves Surface waves are a combination of transverse and longitudinal waves.The waves occur at the surface between water and air.

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