Sound Waves: Exploring Properties, Behavior, and Applications in A-Level Science
What Are Sound Waves?
Sound waves are longitudinal waves that propagate through a medium via compressions and rarefactions.
Properties of Sound Waves
Frequency (
)
)Frequency determines the pitch of a sound, measured in Hertz (Hz):
![\[ f = \frac{1}{T} \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-b73d511df851ecb42dcf05d41e548c51_l3.png "Rendered by QuickLaTeX.com")
Where 
is the time period (s).
Amplitude (
)
)Amplitude determines the loudness of a sound (measured in decibels, dB).
Speed of Sound (
)
The speed depends on the medium:
![\[ v = f\lambda \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-0e0439dca4b9c148fa6c93db542fe1e9_l3.png "Rendered by QuickLaTeX.com")
Where:
- : Speed (m/s)
- : Frequency (Hz)
: Wavelength (m)
: Wavelength (m)Behavior of Sound Waves
Reflection (Echoes)
Sound waves bounce off surfaces, creating echoes when the time delay exceeds 0.1s.
Refraction
Sound waves bend when moving between mediums with different densities (e.g., air to water).
Diffraction
Sound waves spread around obstacles when 
obstacle size.
Applications of Sound Waves
Music
Understanding harmonics (
) enhances instrument design.
Engineering
Ultrasonic waves (
) are used in:
- Non-destructive testing
- Precision cleaning
Medicine
Ultrasound imaging uses:
![\[ \text{Depth} = \frac{vt}{2} \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-17a7978754cea9aef09fc3868c9fc934_l3.png "Rendered by QuickLaTeX.com")
where 
is echo return time.
Example Problem
A sound wave has 
and 
. Find 
:
- Formula:
- Calculation:
![\[ v = f\lambda \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-26ce7e2f003b1f0407f027cbae9d7faf_l3.png "Rendered by QuickLaTeX.com")
![\[ v = 500 \times 0.68 = 340\, \text{m/s} \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-7b60edb1b530cc5b7992ca9b6c646622_l3.png "Rendered by QuickLaTeX.com")
Common Mistakes
- Using inconsistent units (e.g., cm with m/s)
- Neglecting temperature effects on (
) - Confusing longitudinal (sound) with transverse (light) waves
)Practice Questions
- Calculate for
and 
- Explain how piezoelectric crystals generate ultrasound
- Describe SONAR principle using
and 
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