Basics of Waves

Understanding Waves

• Waves transfer energy from one place to another without transferring matter.
• Examples: Light waves from a phone screen to the eye, sound waves from speakers to the ear.
• Our brain interprets this energy as information (images, sounds).

Wave Motion

• Waves vibrate or oscillate to travel.
• Displacement-Distance Graph:
  • Distance: How far the wave has traveled from the starting point.
  • Displacement: How far the wave has moved from the equilibrium point (up or down).
  • Amplitude: Maximum displacement from the equilibrium point.
  • Wavelength: Distance of one complete oscillation (could be from equilibrium up, down, and back up or from crest to crest).
  • Crest: The highest point of the wave.
  • Trough: The lowest point of the wave.

Displacement-Time Graph

• Similar to displacement-distance graph but time is on the x-axis.
• Time Period: Time for one complete oscillation.

Frequency Calculation

• Frequency (measured in Hertz) = Number of complete oscillations per second.
• Formula:
  • Frequency = 1 / Time Period
  • Time Period = 1 / Frequency
• Example:
  • If Time Period = 0.5 seconds, Frequency = 2 Hz (1 / 0.5).
  • If Frequency = 4 Hz, Time Period = 0.25 seconds (1 / 4).

Wave Speed Calculation

• Wave Speed = Wavelength x Frequency.
• Example:
  • For a sound wave with Frequency = 400 Hz and Wavelength = 70 cm (0.7 m):
  • Wave Speed = 0.7 m x 400 Hz = 280 m/s.

Types of Waves

Transverse Waves

• Oscillations are perpendicular to the direction of energy transfer.
• Examples:
  • Electromagnetic waves (light, radio), water waves, guitar strings.

Longitudinal Waves

• Oscillations are parallel to the direction of energy transfer.
• Results in regions of compression and rarefaction.
• Examples:
  • Sound waves, seismic P waves.

Conclusion

• Recap of key concepts about waves, their types, and calculations.