Waves Lecture Notes

Introduction to Waves

• Waves transfer energy and information.
• A wave is a disturbance.
• Key parts of a wave:
  • Crest: The top part of the wave.
  • Trough: The bottom part of the wave.
  • Amplitude: Distance from the peak to the midpoint of the wave.
  • Wavelength: Distance between two peaks or two troughs.

Wave Calculations

• Speed of the Wave: Calculated by multiplying wavelength by frequency.
• Frequency:
  • Number of cycles per second.
  • Calculated as cycles divided by time.
  • Measured in Hertz (Hz) or 1/seconds.
• Period:
  • Time to complete one cycle.
  • Calculated as total time divided by number of cycles.
  • Measured in seconds.
• Relationship: Frequency is the reciprocal of the period (Frequency = 1/Period).

Transverse Waves

• Definition: Waves where oscillations are perpendicular to the direction of wave motion.
• Examples:
  • Water waves (e.g., ocean waves at the beach).
  • Electromagnetic (EM) waves: Light, radio, infrared, X-rays, gamma rays, ultraviolet rays.
  • A plucked string oscillates up and down (transverse wave).

Longitudinal Waves

• Definition: Waves where oscillations are parallel to the direction of wave motion.
• Characteristics:
  • Regions of compression and rarefaction (expansion).
  • Example: Sound waves are longitudinal, pressure waves.
  • Sound waves consist of regions of high pressure (molecules close together) and low pressure (molecules spread out).

Summary

• Transverse waves: Oscillations perpendicular to wave direction.
• Longitudinal waves: Oscillations parallel to wave direction.
• Examples of each type highlight the differences in wave motion and oscillation direction.