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Understanding Waves and Their Properties

May 21, 2025

Waves and Their Properties

Types of Waves

  • Transverse Waves

    • Direction of vibration is perpendicular to propagation.
    • Examples: Water waves, seismic secondary waves, electromagnetic waves.
    • Demonstration: Shake a spring up and down.
    • Key Points: Crest (highest peak), Trough (lowest peak).

  • Longitudinal Waves

    • Direction of vibration is parallel to propagation.
    • Examples: Sound waves, seismic primary waves.
    • Demonstration: Shake a spring forward and backward.
    • Key Points: Compression (particles close, high pressure), Rarefaction (particles apart, low pressure).

Describing Waves

  • Amplitude (A): Distance from equilibrium to peak, indicates energy.
  • Wavelength (λ): Distance between consecutive peaks, measured in meters.
  • Frequency (f): Number of waves per second, measured in Hertz (Hz).
  • Period (T): Time for one cycle, measured in seconds.
  • Wave Speed (v): Distance traveled per unit time, calculated as v = λf.

Wave Fronts

  • Lines connecting identical points in waves.
  • Demonstration: Ripple tank.

Reflection and Refraction

  • Reflection: Change in wave direction upon hitting an obstacle, speed and wavelength remain constant.
  • Refraction: Change in wave direction when passing between media of different densities.
  • Diffraction: Spreading of waves around obstacles or through gaps.

Light Waves

Properties

  • Transverse and electromagnetic.
  • Speed in vacuum: 3 × 10^8 m/s.

Reflection and Refraction

  • Reflection: Follows wave reflection rules.
  • Refraction: Change in speed and wavelength when passing through different media.
  • Critical Angle and Total Internal Reflection: Conditions where light is entirely reflected inside a medium.

Lenses

  • Converging Lens: Focuses light to a point.
  • Diverging Lens: Spreads light out.
  • Images: Real (can be projected) and virtual (cannot be projected).

Dispersion

  • White light splits into colors when passed through a prism.
  • Different colors have different wavelengths.

Electromagnetic Spectrum

Spectrum

  • Includes radio waves to gamma rays.
  • Arranged by wavelength and frequency.
  • Higher frequency waves are more ionizing and harmful.

Uses and Effects

  • Radio Waves: Communication.
  • Microwaves: Cooking, radar.
  • Infrared: Remote controls, thermal imaging.
  • Visible Light: Vision, photography.
  • Ultraviolet: Sterilization, tanning.
  • X-rays: Medical imaging.
  • Gamma Rays: Sterilizing equipment, cancer treatment.

Sound Waves

Properties

  • Longitudinal waves.
  • Require a medium to travel.
  • Speed varies in different media (solids > liquids > gases).

Production and Characteristics

  • Produced by vibrating sources.
  • Comprised of compressions and rarefactions.

Experiments

  • Measure speed using echoes and reflections.

Pitch, Loudness, and Quality

  • Frequency: Determines pitch.
  • Amplitude: Determines loudness.

Ultrasound

  • Frequencies above 20,000 Hz.
  • Applications: Sonar, medical imaging, industrial cleaning.

These notes cover the fundamental principles needed to understand waves, their properties, and practical applications across various media and technologies. The focus should be on understanding how vibrations, speed, and frequency relate to the different types of waves and their behaviors.

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