2 14.1 Wave PropertiesEnergy can be transferred by particles or by waves.Types of Waves - Mechanical, Electromagnetic, & MatterMechanical waves require medium to travel, such as air, water, & springs or ropes.
3 EM waves do not require medium. Ex: light waves, radio waves & x-rays.They all travel at speed of light (c).Matter waves involve electrons & other particles that demonstrate wave like properties under certain conditions.
4 Will be studied under Quantum Mechanics. Three types of mechanical waves.Transverse - particles vibrate perpendicularly to direction of motion of wave.Longitudinal - particles travel in direction of wave.Surface - mixture of transverse & longitudinal.
5 Transverse waves do not travel through earth’s center, which indicates center is fluid. Wave pulse - a single disturbance travels through medium.Wave train or traveling wave - a series of pulses at regular interval.
7 Measuring a WavePeriod, - time required for motion to repeat itself.Frequency, f - number of complete vibrations per second. f = 1 / Wavelength, - distance from crest to crest or trough to trough.
8 Crests - high points of wave Trough - low points of waveWhen time interval is one period, wave would move a distance of 1 wavelength.Velocity - given by v = / T or v = fAmplitude - maximum displacement from rest or equilibrium position.
9 Speed of sound in air depends on temperature. Speed of light is always constant.3.00E8 m/s = cEx. Prob 333Prac Prob 335
10 14.2 Wave Behavior -Boundaries When wave reaches boundary of media, it may be reflected or pass.Speed & change when wave enters new medium.FigJunction of two springs is a boundary between two media.
11 A pulse reaching boundary (a) is partially reflected & partially transmitted. (free) Fig A pulse is shown as it approaches a rigid wall (a) & as it is reflected from wall (b).Notice amplitude is almost same but reflected pulse is inverted.
12 When medium changes, wave energy is both reflected & transmitted. Waves passing from one medium to another have same f.The change depends on v change so that f = v/ is constant.Prac Prob 337
14 Superposition of Waves Principle of superposition - displacement of a medium caused by two or more waves is algebraic sum of displacements caused by individual waves.Interference - result of superposition.
15 Destructive interference occurs when crest meets trough. Resultant wave is smaller. Fig 14-11a 338Constructive interference occurs when waves meet crest to crest or trough to trough.Resultant wave is larger. Fig 14-11b 338
16 If waves are opposite & equal magnitude, result is 0. Fig 14-11c 338Continuous waves – from a region of higher speed to one with lower speed.Fig
17 Standing Waves Node - pt that is undisturbed. Medium is not displaced as waves pass.Antinode - pt of max displacement.Standing wave has stationary nodes & antinodes.It is result of identical waves traveling in opposite directions. Fig
18 Waves in Two Dimensions Law of reflection - angle at which a wave approaches a barrier is equal to angle at which it is reflected.FigNormal - to barrier.Angle of incidence - angle between incident ray & normal.
19 Angle of reflection - angle between normal & reflected ray. Refraction - change of wave direction at boundary between two media.FigDiffraction bending of waves around barrier.Fig & Fig
20 BibliographyPhysics: Principles and Problems, GlencoeDigital Curriculum