Presentation on theme: "Waves A wave is a rhythmic disturbance that carries energy through matter or space."— Presentation transcript:
1 WavesA wave is a rhythmic disturbance that carries energy through matter or space.
2 Two Categories of Waves Mechanical WavesA wave that requires a medium (matter).Electromagnetic Waves(Coming Soon, Chapters 16 – 19)
3 Types of Mechanical Waves TransverseA wave that vibrates perpendicular to the motion of the waves.
4 Types of Mechanical Waves LongitudinalA wave that vibrates parallel to the motion of the wave.
5 Types of Mechanical Waves SurfaceA wave that is a combination of both transverse and longitudinal waves (overall motion is circular).
6 Wave Properties Amplitude – maximum displacement from equilibrium. The crest (compression) is highest point of the wave and the trough (rarefaction) is the lowest point of the wave.Wavelength – The distance of one complete wave cycle (oscillation).
7 Wave MeasurementsFrequency (f) – Number of complete oscillations in one second; measured in Hertz.Period (T) – The time elapsed in one complete wave cycle (oscillation).Wave speed (v) – The product of the wavelength and frequency or, the wavelength divided by the period.
8 Wave BehaviorReflection – the bouncing back of a wave as it encounters a boundary.Fixed point reflectionFree boundary reflection
9 Wave BehaviorDiffraction – the spreading of waves around a barrier or object.
10 Wave BehaviorRefraction – the change in the direction of a wave as it enters a different medium.
11 Wave Behavior Interference Principle of Superposition – the combination of two or more waves into a single wave.Constructive interferenceDestructive interferenceStanding waves (nodes & antinodes)
12 Sound WavesSound waves are longitudinal pressure variations that are transmitted through matter.Sound is produced by vibrating objects.
13 Properties of Sound Waves Sound Level (loudness)The amplitude of a sound wave.Measured in decibels (dB). A 20 dB increase equals a 10 time increase in pressure amplitude.PitchDescribes the frequency of vibrations.More vibrations = higher pitch; less vibrations = lower pitch.
14 The Doppler ShiftThe apparent change in the pitch of a sound as it moves towards or away from an observerPitch increases as a sound moves toward an observer.Pitch decreases as a sound moves away from an observer.
15 Sound & Music Closed-pipe resonators A resonating tube (column) with one closed end and one open end.Minimum resonance frequencies occur at one-fourth of the wavelength, then at half-wavelength intervals.Column lengths of (1/4)λ, (3/4)λ, (5/4)λ, etc., will result in resonance.
16 Sound & Music Open-pipe resonators A resonating tube (column) with both ends open.Minimum resonance frequencies occur at one-half of the wavelength, then at half-wavelength intervals.Column lengths of (1/2)λ, λ, (3/2)λ, 2λ, etc., will result in resonance.
17 Sound & Music Fundamental (f1) Harmonics Octave The lowest frequency of resonance.HarmonicsHigher frequencies that are multiples of the fundamental frequency.OctaveThe difference in frequency of two musical notes with ratio of 1:2.
18 Sound & Music Beats Oscillations in wave amplitude. The frequency of the beat is the magnitude of the difference between the two frequencies.