IB MYP 4-5 Physics- Longitudinal and transverse waves- Study Notes - New Syllabus
IB MYP 4-5 Physics-Longitudinal and transverse waves- Study Notes
Key Concepts
- Longitudinal and transverse waves
Longitudinal and Transverse Waves
Longitudinal and Transverse Waves
A wave is a disturbance that transfers energy from one place to another without the transfer of matter.
1. Longitudinal Waves
- In a longitudinal wave, the particles of the medium vibrate parallel to the direction of wave propagation.
- Regions of compression (particles close together) and rarefaction (particles far apart) are formed.
- Examples: Sound waves in air, seismic P-waves, ultrasound.
Key feature: Oscillations ↔ (back and forth) in the same direction as wave travel.
2. Transverse Waves
- In a transverse wave, the particles of the medium vibrate perpendicular to the direction of wave propagation.
- They have crests (high points) and troughs (low points).
- Examples: Light waves, water waves, seismic S-waves, waves on a rope.
Key feature: Oscillations (up and down) while wave travels →.
Longitudinal vs. Transverse Waves
| Feature | Longitudinal Waves | Transverse Waves |
|---|---|---|
| Direction of particle vibration | Parallel to wave direction | Perpendicular to wave direction |
| Main features | Compressions & Rarefactions | Crests & Troughs |
| Examples | Sound waves, ultrasound, P-waves | Light waves, water waves, S-waves |
Example:
Sound travels through air as a longitudinal wave. What happens to air particles when a loudspeaker produces sound?
▶️ Answer/Explanation
Air particles vibrate back and forth parallel to the sound wave’s direction.
They form compressions (high pressure) and rarefactions (low pressure).
Final Answer: \(\boxed{\text{Particles oscillate parallel to the wave direction.}}\)
Example:
A water wave moves forward. In which direction do water particles move as the wave passes?
▶️ Answer/Explanation
Water particles move up and down (perpendicular to the wave motion).
The wave itself transfers energy forward across the water surface.
Final Answer: \(\boxed{\text{Particles oscillate up and down, wave travels forward.}}\)
Example:
Which type of wave (longitudinal or transverse) can travel through space (vacuum)? Why?
▶️ Answer/Explanation
Sound (longitudinal) needs a medium like air → cannot travel in vacuum.
Light (transverse electromagnetic wave) does not need a medium → can travel through vacuum.
Final Answer: \(\boxed{\text{Transverse (light) waves can travel through vacuum.}}\)