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Waves & Energy Transfer

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Presentation on theme: "Waves & Energy Transfer"— Presentation transcript:

1 Waves & Energy Transfer
Chapter 14

2 14.1 Wave Properties Energy can be transferred by particles or by waves. Types of Waves - Mechanical, Electromagnetic, & Matter Mechanical 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.

6 Two Types of Waves

7 Measuring a Wave Period,  - 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 wave When time interval is one period, wave would move a distance of 1 wavelength. Velocity - given by v =  / T or v = f Amplitude - 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 = c Ex. Prob 333 Prac 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. Fig Junction 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

13 Wave Boundaries Less to More More to less

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 338 Constructive 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 338 Continuous 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. Fig Normal -  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. Fig Diffraction bending of waves around barrier. Fig & Fig

20 Bibliography Physics: Principles and Problems, Glencoe Digital Curriculum

21 Longitudinal or Compression

22 Light Propagation

23 Wavelength

24 Fixed Boundary

25 Free End

26 Interference

27 Less to More Dense

28 Longitudinal

29 Transverse

30 Surface Waves or Water Waves

31 Destructive & Constructive

32 Nodes & Antinodes

33 Standing Wave

34 Diffraction

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