Basics of Waves

Introduction

• Waves transfer energy from one place to another without transferring matter.
• Examples: Light waves (phone screen to eye) and sound waves (speakers to ear).

Wave Properties

• Displacement-Distance Graph: Shows wave oscillation.
  • Displacement: Distance from the equilibrium point (up or down).
  • Distance: How far the wave has traveled from the starting point.
• Amplitude: Maximum displacement.
• Wavelength: Distance of one entire oscillation (equilibrium up-down-up or crest to crest).
• Crest: Top of the wave.
• Trough: Opposite of the crest.

Displacement-Time Graph

• Similar to displacement-distance graph but with time on the x-axis.
• Time Period: Time for one complete oscillation.
• Frequency: Number of oscillations per second (measured in Hertz).
  • Formula: Frequency = 1 / Time Period
  • Example: Time Period of 0.5 seconds results in Frequency of 2 Hz.

Calculating Wave Speed

• Formula: Wave Speed = Wavelength × Frequency
  • Example: Sound wave with Frequency of 400 Hz and Wavelength of 70 cm (0.7 m) has a Wave Speed of 280 m/s.

Types of Waves

• Transverse Waves: Oscillations are perpendicular to the direction of energy transfer.
  • Examples: Electromagnetic waves (light, radio), water ripples, guitar strings.
• Longitudinal Waves: Oscillations are parallel to the direction of energy transfer, creating compression and rarefaction regions.
  • Examples: Sound waves, seismic P waves.

Summary

• Waves transport energy without transporting matter.
• Key properties: amplitude, wavelength, frequency, and wave speed.
• Transverse vs. Longitudinal waves.
• Useful equations for understanding and calculating wave behavior.