Physics Sound Waves and Longitudinal Waves

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Questions and Answers

What is the relationship between sound intensity and amplitude of oscillations?

Increased intensity results in decreased amplitude oscillations.

Higher intensity correlates with larger amplitude oscillations. (correct)

Intensity is independent of amplitude.

Amplitude is solely determined by the frequency of the sound wave.

Which characteristic of a sound distinguishes different types of instruments when they produce the same pitch and loudness?

Frequency

Loudness

Intensity

Quality (Timbre) (correct)

How does pitch change with respect to the frequency of a sound wave?

Pitch is not affected by frequency.

Pitch is higher with lower frequencies.

Pitch increases with higher frequencies. (correct)

Pitch is lower with higher frequencies.

What does the logarithmic scale conversion for sound level measure?

Sound intensity relative to threshold hearing. Signup and view all the answers

What is true regarding destructive interference in sound waves?

It creates regions of zero or diminished waves. Signup and view all the answers

What happens to sound waves in a vacuum?

They cannot travel at all. Signup and view all the answers

Which factor primarily affects the speed of sound in a medium?

The density of the medium. Signup and view all the answers

What is the primary characteristic of a longitudinal wave?

Particles move parallel to the direction of the energy transport. Signup and view all the answers

What defines the amplitude of a wave?

The maximum displacement from equilibrium. Signup and view all the answers

If the frequency of a sound wave is increased, what happens to its wavelength, assuming the speed of sound remains constant?

The wavelength decreases. Signup and view all the answers

What are spherical waves characterized by?

Surfaces of common phase that are spherical. Signup and view all the answers

According to the speed of sound in various mediums, which of the following mediums has the highest speed of sound?

Aluminium Signup and view all the answers

In which form is sound wave energy primarily transported?

By compressions and rarefactions. Signup and view all the answers

What is a characteristic of spherical waves?

They exhibit spherical symmetry. Signup and view all the answers

In which of the following applications are spherical waves notably utilized?

Modeling sound fields in acoustics. Signup and view all the answers

What happens when sound waves reflect off a surface?

They may produce echoes or reverberations. Signup and view all the answers

How does diffraction of sound waves change with wavelength?

Diffraction increases with increasing wavelength. Signup and view all the answers

For significant diffraction to occur, what should the size of the obstacle or opening be like in relation to wavelength?

Comparable to the wavelength. Signup and view all the answers

What does refraction of sound waves involve?

A change in direction accompanied by speed and wavelength changes. Signup and view all the answers

What defines an echo in the context of sound waves?

A sound heard more than 0.1 seconds after the original sound. Signup and view all the answers

How do waves interact with one another at the point of interference?

They combine their energies to create interference patterns. Signup and view all the answers

Study Notes

Sound

Sound waves can be transmitted through various materials like air, water, wood, and biological tissue.
Sound waves require a medium for transmission; they cannot travel in a vacuum.
Sound is a longitudinal wave; its propagation involves compression and rarefaction patterns.
Compression occurs when molecules are tightly packed together, while rarefaction occurs when molecules are spaced apart.

Longitudinal Waves

Longitudinal waves involve particle motion parallel to the direction of energy transport.
Sound waves in air and fluids are longitudinal because their particles vibrate parallel to the sound wave's direction.

Basic Terminology of Sinusoidal Vibration

Time Period (T): The time taken for one complete cycle of periodic motion, measured in seconds.
Frequency (f): The number of cycles per second, measured in Hertz (Hz).
Amplitude (A): The maximum displacement from equilibrium position during a cycle of periodic motion, measured in meters or millimeters.
Wavelength (λ): The distance between to successive crests or troughs of a wave, measured in meters, millimeters, micrometers or nanometers.

Speed of Sound

Speed is calculated as distance travelled per unit time.
Speed increases with higher density.
Speed of sound varies depending on the medium. A table showing the speed of sound in different mediums at 20°C is provided.

Spherical Waves

Spherical waves have surfaces of common phase that are spheres, originating from a central point.
Spherical waves have spherical symmetry, meaning the strength is the same in all directions as the source distance increases.
Spherical waves can be coherent (maintain a constant phase relationship). Coherent waves can produce interference patterns (where intensity is either increased or reduced).
Non-coherent waves, when superimposed, do not produce permanent interference patterns.

Reflection, Refraction, Diffraction, and Interference

Reflection: When a sound wave hits a boundary, part of it reflects, leading to echoes or reverberations. Reverberations are more common in smaller enclosed spaces (<17m). Echoes might be heard in larger spaces and are separated by >0.1 second from the original sound.
Refraction: Sound waves can refract (bend) as they pass from one medium to another, changing speed and wavelength.
Diffraction: Sound waves can bend around obstacles or through openings, particularly when the wavelength is comparable to the size of the opening or obstacle.
Interference: When two sound waves meet, their energies combine to create interference patterns. Constructive interference results in increased intensity; destructive interference results in decreased or zero intensity.

Characteristics of Sound Waves

Intensity: The power per unit area carried by a sound wave; the amplitude influences intensity.
Pitch: A characteristic distinguishing sounds; depends on the frequency (higher frequency = higher pitch).
Quality/Timbre: The characteristic distinguishing different sound sources having the same intensity and pitch; dependent on the waveform (waveform shape).

Loudness

Loudness depends on the amplitude of the sound wave; higher amplitude = higher perceived loudness.
Sound levels are often measured in decibels (dB), using a logarithmic scale to accommodate the wide range of intensities humans can detect, with the reference intensity 1.00 × 10-12 W/m².

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Description

Explore key concepts related to sound waves and their transmission through different materials. This quiz covers sound as a longitudinal wave, its basic terminology, including time period, frequency, and amplitude, as well as the nature of sound waves in various media.