14.2 Sound Waves

• The equation relating speed, frequency, and wavelength of a sound wave is $v =$$f \lambda$.


  True
• The speed of a sound wave depends on the medium's density and temperature.
• Sound waves are an example of longitudinal waves.
• The amplitude of a sound wave corresponds to its loudness.
• Decibels measure the relative loudness of a sound on a logarithmic scale.
• What is the unit of sound intensity?

  W/m²
• Decibels (dB) measure the relative loudness of a sound on a logarithmic
• The formula to calculate the sound level in decibels is $L =$$10 \log_{10} \left( \frac{I}{I_{0}} \right)$, where `L` is the sound level, `I` is the sound intensity, and `I_0` is the reference intensity
• The relationship between sound intensity and decibel level is expressed by the equation L = 10 \log_{10} \left( \frac{I}{I_{0}} \right)</latex>, where `L` is in decibels
• The general Doppler formula for frequency is f' = f \frac{v \pm v_{o}}{v \mp v_{s}}</latex>, where `f'` is the observed frequency, `f` is the source frequency, `v` is the wave speed, $v_{o}$ is the observer's speed, and $v_{s}$ is the source's speed
• What happens to the wave intensity during constructive interference?

  Increases
• Resonance occurs when a system is driven at its natural frequency
• Sound waves require a medium to travel.
• What is the primary cause of sound wave production?

  Vibration
• What type of wave has particle movement parallel to wave propagation?

  Longitudinal wave
• What property of a sound wave determines its pitch?

  Frequency
• What is the reference intensity used in decibel calculations?

  $10^{ - 12}$ W/m²
• Properties of sound waves and their effects

  1️⃣ Speed relates to medium density

  2️⃣ Frequency affects pitch

  3️⃣ Wavelength influences pitch

  4️⃣ Amplitude determines loudness
• What is sound intensity measured in?

  W/m²
• What is the sound level in decibels if the sound intensity is equal to the reference intensity?

  0 dB
• What are the units of sound intensity?

  W/m²
• What does the Doppler effect describe?

  Change in frequency
• Match the Doppler effect case with its example:

  Moving source towards observer ↔️ Car horn approaching you

  Moving source away from observer ↔️ Car horn moving away from you

  Observer moving towards source ↔️ You approaching a stationary ambulance

  Observer moving away from source ↔️ You moving away from a stationary ambulance
• Destructive interference occurs when two waves with opposite phases overlap.


  True
• What happens to the amplitude of a system during resonance?

  Increases dramatically
• Match the concept with its characteristics:

  Resonance ↔️ Large amplitude response, energy efficiently transferred

  Standing Waves ↔️ Fixed pattern of antinodes and nodes
• What type of waves are sound waves?

  Longitudinal mechanical waves
• Steps in the production of sound waves

  1️⃣ Object vibrates

  2️⃣ Medium compresses and expands

  3️⃣ Pressure variations propagate

  4️⃣ Sound waves are created
• Frequency is measured in Hertz (Hz).

  True
• The speed of a sound wave is constant in all media.

  False
• Sound intensity measures the power of a sound wave per unit area.


  True
• In transverse waves, particles move parallel to the direction of wave travel.

  False
• The reference intensity (I_0) used in decibel calculations is $10^{ - 12}$ W/m²


  True
• The decibel scale is linear.

  False
• Decibels measure the absolute amount of energy in a sound wave.

  False
• In the Doppler effect, the plus sign is used for receding motion.

  False
• Superposition is the principle that when two or more waves overlap, their displacements add together
• Match the type of interference with its description:

  Constructive Interference ↔️ Waves with the same phase overlap

  Destructive Interference ↔️ Waves with opposite phase overlap
• Standing waves have fixed points of maximum and minimum amplitude called antinodes and nodes.


  True