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1. What Waves Are:
1. What Waves Are:
A wave is a repeating disturbance that transfers energy from one place to another. Like when you shake one end of a rope, the wave moves but the rope itself doesn’t travel.
Waves do not carry matter, only energy.
2. Types of Waves:
2. Types of Waves:
Mechanical Waves – Require a medium (solid, liquid, or gas) to travel through.
Mechanical Waves – Require a medium (solid, liquid, or gas) to travel through.
Examples:
Sound waves (travel through air). They are mechanical and longitudinal (Compressional).
Water waves (travel through water)
Seismic waves are mechanical waves that move through earth's crust.
Electromagnetic Waves – Do not require a medium; can travel through space.
Electromagnetic Waves – Do not require a medium; can travel through space.
Examples:
Light
Radio waves
X-rays
3. Properties of Waves:
3. Properties of Waves:
Wavelength –
Distance from one crest to the next (or one compression to the next).
Frequency –
How many waves pass a point in a second (measured in Hertz, Hz).
Wavelength and energy have an inverse relationship: Shorter waves have more energy. Longer waves have less energy.
Amplitude –
Height of the wave; related to the energy of the wave. More amplitude, means more energy.
Speed –
How fast a wave travels, depends on the medium.
4. Types of Wave Motion
4. Types of Wave Motion
Transverse Waves
Transverse Waves
Particles move perpendicular to the wave motion.
Examples: Light waves, ocean waves, stadium waves, radio and microwaves.
Also, earthquake S-waves (secondary or shear waves) are transverse waves.
Longitudinal Waves
Longitudinal Waves
Particles move parallel to the wave motion.
Example: Sound waves and seismic p-waves
Reminder: Longitudinal waves also known as compressional waves.
5. Wave Behavior
5. Wave Behavior
Reflection
Waves bounce off surfaces (e.g., echo of sound, light in a mirror).
Diffraction
Waves spread out when passing through an opening or around an object.
Interference – Waves can add together (constructive) or cancel each other out (destructive).”
Destructive Interference
Destructive Interference
Interference – Waves can combine, creating constructive (bigger waves) or destructive (smaller waves) interference.
6. Sound Waves vs. Light Waves
6. Sound Waves vs. Light Waves
Sound Waves
Sound Waves
Mechanical, longitudinal, need a medium, travel faster in solids than in air.
Sound travels faster in hot air!
Sound travels faster in hot air!
Sound travels farther at night!
Sound travels farther at night!
Sound moves fastest in...
Sound moves fastest in...
Solids! The molecules in a solid are closer together. This allows energy to be tranferred efficiently and quickly! See the diagram to the right! ➡️
Light Waves
Light Waves
Electromagnetic
transverse
do not need a medium
travel fastest in a vacuum
There is nothing faster than the speed of light! Light moves a 3 x 10^8 m/s.
7. Seismic Waves and Earthquakes!
7. Seismic Waves and Earthquakes!
When an earthquake happens, energy travels through Earth as seismic waves.
These waves cause the ground to shake.
Scientists use special tools called seismographs to record seismic waves.
Types of Seismic Waves:
Types of Seismic Waves:
P-Waves (Primary Waves)
P-Waves (Primary Waves)
Fastest seismic waves. First waves detected during an earthquake
P-waves are compressional/longitudinal waves
Travel through solids, liquids, and gases
P-waves are longitudinal/compressional.
Move by pushing and pulling (back-and-forth motion)
S-Waves (Secondary or Shear Waves)
S-Waves (Secondary or Shear Waves)
Slower than P-waves
S-waves are transverse waves.
Travel only through solids
S-waves shake the ground side to side or up and down
Cannot travel through Earth’s liquid outer core
Surface Waves are generated when P and S waves reach the Earth's surface.
Surface Waves are generated when P and S waves reach the Earth's surface.
Travel along Earth’s surface
Slowest, but cause the most damage and destruction
Create rolling or shaking motion
Responsible for most building destruction during earthquakes
Love Wave
Love Wave
Love waves are surface waves. They move the ground side to side in a horizontal motion.
They are often the most damaging because buildings are not designed to handle strong sideways movement.
These waves travel only near Earth’s surface and need layers of rock to move through.
Rayleigh Wave
Rayleigh Wave
This is a surface wave. Rayleigh waves make the ground move in a rolling motion, like ocean waves.
The ground moves up and down and back and forth at the same time.
These waves travel along Earth’s surface and can move through both solid ground and areas under water.
Because they lose energy slowly, Rayleigh waves can travel long distances and may circle the Earth after very large earthquakes.
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