Chapter 15
Characteristics of Waves Waves disturbances that carry energy through matter or space Waves transfer energy. The energy being transferred may spread out as waves travel.
Characteristics of Waves Some waves travel through mediums Mediums can be solids, liquids, gases, or a combination of these states Waves that require mediums to travel through are called mechanical waves Electromagnetic waves are the only waves that do not need to travel through a medium
Characteristics of Waves Transverse Waves waves in which the wave motion is perpendicular to the particle motion Ex: Light waves
Characteristics of Waves Parts of a Transverse Wave Crests Troughs Wavelength (Greek symbol lambda ) Amplitude
Wave Frequency Frequency # of wave crests that pass one place each second Units: Hertz (Hz), meaning cycles per second Frequency increases as wavelength decreases. Frequency Period Equation: Frequency Period (the time it takes for one full wavelength of a wave to pass.in seconds)
Wave Velocity Calculating how quickly a wave is traveling in a particular direction Equation: = velocity = frequency = wavelength
Longitudinal Waves Longitudinal waves matter that vibrates in the same direction of the traveling wave Ex: Sound Waves Parallel Motion
Longitudinal Waves Crowded area compression Spread out area rarefaction (rare faction, not to be confused with refraction) Contains wavelengths and frequencies
Sound Waves Sound waves depend on: The type of medium Temperature of the medium Sound properties that can change: Frequency & Pitch (Ex: Doppler Effect) Intensity & Loudness (Decibel Scale)
Surface Waves Particles in this type of wave move both perpendicularly and parallel to the direction in which the wave travels Tend to move through two types of mediums
Wave Interactions Chapter 15 Section 3
Wave Interactions Reflection the bouncing back of a wave when it meets a surface or boundary
Wave Interactions Diffraction the bending of waves as they pass an edge The amount of diffraction depends on its wavelength and on the size of the barrier/opening
Wave Interactions Refraction the bending of waves as they pass through one medium to another at an angle An example of an optical illusion
Wave Interactions Constructive Interference when waves overlap, the result is a wave whose amplitude is the sum of the amplitudes of the two individual waves http://physics.bu.edu/~duffy/py105/waveinterference.html
Wave Interactions Destructive Interference when the crest of one wave meets the trough of another wave, the resulting wave has a smaller amplitude Waves amplitudes tend to cancel each other out http://physics.bu.edu/~duffy/py105/waveinterference.html
Wave Interactions Standing Wave occur from interference between a wave and a reflected wave Causes a medium to vibrate in a stationary or loop pattern http://www1.union.edu/newmanj/physics100/light%20as%20a%20wave/light_as_a_wave.htm
Sound Chapter 16
Sound Waves Sound waves are caused by vibrations and carry energy through a medium An example of a longitudinal wave Waves can spread out in all directions Their speed depends on its medium
Sound Waves Sound waves depend on the following: The wave speed Temperature of the medium Pitch (ex: Doppler effect) Intensity (Decibel Scale)
Loudness is determined by intensity Loudness: depends on the energy contained in the wave Intensity: the rate at which the wave transmits energy Decibel Levels 120 (threshold of pain) Sound Waves
Sound Waves Pitch is determined by frequency Pitch is how high or low a sound is High pitch: rapid vibration and low pitch is vice versa Infrasound: pitch below range of human hearing Ultrasound: pitch above range of human hearing
Sound Waves and Musical Musical instruments rely on standing waves Resonance: when two objects naturally vibrate at the same frequency Depends on shape, size, mass and type of material Instruments