Waves: Sound and Light crest an-- node WAVES MOVE ENERGY, NOT MATTER! travelling wave-energy moves in node standing wave-energy moves in plane trough plane of paper, wave moves le-right of paper but the waves are staonary (guitar string) node: point of zero amplitude (energy) Wave Characteris9cs an--node: point of maximum amplitude (energy) diffrac-on: wave “bends” around opening in refrac-on: wave bends when reflec-on: wave bounces from surface a boundary entering a new medium. Speed and wavelength changes. Waves add CONSTRUCTIVELY or DESTRUCTIVELY Light and sound waves have a constant speed unless the waves change media. sound: 343 m/s in air light: 3 x 108 m/s in vacuum (similar value in air) 1 f = T T is period in seconds 1 f is frequency in Hz T = f λ is wavelength in meters v = λ f v is speed in m/s destruc-ve both construc-ve SOUND longitudinal wave: wave moves Sound Characteriscs leg-right and maer is displaced right-leg-right. All objects have a NATURAL frequency of vibraon and they can be made to the amplitude pressure waves: dark lines are vibrate (produce sound) by an outside source. of the wave tells you compressed air. This is known as a FORCED VIBRATION. how LOUD the sound is; larger means louder RESONANCE occurs when a forced vibraon Sound waves are a type of MECHANICAL wave known as LONGITUDINAL waves matches the natural frequency of vibraon. Mechanical waves move through solids, liquids or gases. SOUND CANNOT TRAVEL IN A VACUUM. In longitudinal waves the maer displacement Is parallel to the direc-on of wave mo-on TRANSVERSE mechanical waves displace maer perpendicular to the direc-on of wave mo-on LIGHT Light Characteriscs It has an ELECTRIC field and a MAGNETIC field. It behaves like a par-cle and a wave. Photons are the fundamental par-cle of light. Some-mes they behave like par-cles, some-mes like waves. The DOUBLE SLIT experiment established the wave like proper-es of light. The PHOTOELECTRIC EFFECT established the par-cle like behavior of light (Einstein). This effect says light must behave as a par-cle to knock electrons off of the surface of a metal. Young’s double slit experiment. Light wave through two slits adds construc-vely and destruc-vely beyond the slits. light waves are TRANSVERSE WAVES that can travel without a medium. This type of transverse wave is known as an ELECTROMAGNETIC wave. high frequency of photons mean higher elec-on speed. high intensity of light means more electrons removed. .