Waves and Energy Transfer

Wave Properties Types of waves Mechanical waves: water waves, sound waves, rope waves(require a medium) Transverse waves: particles vibrate perpendicularly to the direction of motion of wave Longitudinal waves: particles vibrate parallel to the direction of the motion of the wave(compressions and rarefactions) Surface waves: particles move both perpendicularly and parallel to the wave direction

Wave Properties Types of waves Electromagnetic waves: light, X-rays, radio waves(no medium required; travel at light speed) Matter waves: electrons and other particles exhibit matter waves under certain conditions(require quantum mechanics to describe properties)

How are waves produced? A wave pulse is a single disturbance that travels through a medium. A traveling wave can be made by moving the rope or spring side to side. This may also be called a wave train. Waves are produced by a vibrating source.

The Measures of a Wave The shortest time interval during which the motion repeats itself is called the period(T). The frequency of the wave (f or ) is the number of complete vibrations per second measured at a fixed location. It is measured in Hertz or second -1. The frequency and the period are inverses of one another. The wavelength( ) is the shortest distance between points where the wave pattern repeats itself(crest to crest or trough to trough). uction/introductionWaves.html uction/introductionWaves.html

Waves

A wave is measured by its velocity. If it is EMR then its velocity is the speed of light. If it is another kind of wave then V =  The amplitude of a wave is the maximum displacement from the rest or equilibrium position. More amplitude requires more work and a larger amplitude transfers more energy. If the amplitude is doubled, the energy transfer is increased by a factor of 4.

Wave Interference The speed of a mechanical wave depends only on the properties of the medium. The speed of water waves depends on the depth of the water. The speed of rope waves depends on the force exerted on the rope and its mass per unit of length. The speed of sound in air depends on the temperature of the air.

Wave Interference Speed does not change through a given medium even if the amplitude changes. Often the medium changes. When this happens part of the energy is carried into the new medium with the same frequency and part is reflected.

Two kinds of interference Constructive interference occurs when two waves in phase reinforce one another and a larger wave results as they pass one another. rence/constructiveInterference/InterferenceExplanation2.html rence/constructiveInterference/InterferenceExplanation2.html Destructive interference occurs when two waves out of phase encounter one another and the resultant wave is smaller than either wave. rence/destructiveInterference/InterferenceExplanation3. html rence/destructiveInterference/InterferenceExplanation3. html rence/intrfrnc.html rence/intrfrnc.html

Wave Adder waves/waveAdder/WaveAdder1.html waves/waveAdder/WaveAdder1.html

New terms Standing wave: a wave that appears not to move Antinode: a place on a wave not equal to zero Node: a place on a wave where the function is equal to zero; a damper can be placed on a node and there is no change to the wave motion es/standingWaves/standingWaveDiagrams1/St andingWaveDiagrams1.html es/standingWaves/standingWaveDiagrams1/St andingWaveDiagrams1.html

New Terms tandingWaves/standingWaves1/StandingWaves1. html tandingWaves/standingWaves1/StandingWaves1. html tandingWaves/standingWaves2/StandingWaves2. html tandingWaves/standingWaves2/StandingWaves2. html tandingWaves/standingWaves3/StandingWaves3. html tandingWaves/standingWaves3/StandingWaves3. html

More terms Reflected waves are those that bounce back from a barrier. waves/waveReflection/waveReflection.html waves/waveReflection/waveReflection.html Refracted waves are those that are bent as they pass into another medium. Refraction