Overview
This lecture covers the fundamentals of waves, including wave parts, calculations of wave speed, and differences between transverse and longitudinal waves.
Wave Basics
- Waves transfer energy from one place to another without transferring matter.
- Light and sound waves can carry meaningful information to our senses.
Parts of a Wave
- Displacement is how far the wave oscillates from its equilibrium point.
- Amplitude is the maximum displacement from the equilibrium.
- Wavelength is the distance of one complete oscillation (crest to crest or trough to trough).
- Crest is the top point of a wave, while trough is the lowest point.
Understanding Wave Graphs
- A displacement-distance graph uses distance traveled as the x-axis; one oscillation = wavelength.
- A displacement-time graph uses time as the x-axis; one oscillation = time period.
Wave Equations
- Frequency (Hz) = Number of oscillations per second; ( \text{Frequency} = \frac{1}{\text{Time Period}} ).
- Time Period = ( \frac{1}{\text{Frequency}} ).
- Wave speed (m/s) = Wavelength (m) × Frequency (Hz).
Wave Speed Example
- Convert wavelength to meters before calculation (e.g., 70 cm = 0.7 m).
- Wave speed = 0.7 m × 400 Hz = 280 m/s.
Types of Waves
- Transverse waves: Oscillations are perpendicular to the direction of energy transfer (e.g., light, water waves, guitar strings).
- Longitudinal waves: Oscillations are parallel to the direction of energy transfer, causing compressions and rarefactions (e.g., sound, seismic P waves).
Key Terms & Definitions
- Amplitude — Maximum displacement from equilibrium.
- Wavelength — Distance of one complete oscillation.
- Crest — Highest point of a wave.
- Trough — Lowest point of a wave.
- Time Period — Time for one full oscillation.
- Frequency — Number of complete oscillations per second (Hz).
- Wave Speed — Distance a wave travels per second.
- Transverse Wave — Oscillation perpendicular to energy transfer.
- Longitudinal Wave — Oscillation parallel to energy transfer.
Action Items / Next Steps
- Practice labeling parts of a wave on given diagrams.
- Solve sample problems using the wave speed, frequency, and time period equations.