1. Types of Waves
There are two ways we can group waves into different types
based on the relationship of the wave to its medium
mechanical
electromagnetic
surface
based on direction of vibration in comparison to the direction of wave travel
“back-and-forth”
“up-and-down” or “side-to-side”
“circular”

2. Waves and Their Media
Mechanical waves require a medium to move through
the medium can be any form of matter: solid, liquid, gas – even plasma
the wave travels through the medium as the atoms of the medium bump into each other, passing along their energy
based on the way mechanical waves move, we can see that they move faster through denser matter (solids) than they do through less dense matter (gases)

3. Waves and Their Media
Electromagnetic waves do not require a medium to move through – they can move through a vacuum – but they can also move through matter
the wave travels as alternating variations (vibrations) in the strength and direction of electrostatic and magnetic fields
based on the way electromagnetic waves move, we can see that they move fastest in the absence of matter (a vacuum), and faster through less dense materials (gases) than they do through denser matter (solids)

4. Waves and Their Media
Surface waves are a special type of mechanical wave that move along the boundary between two media that have different properties
the wave travels primarily in the denser medium so its behavior is determined mostly by the properties of that medium; however,
the atoms at the boundary of a material are not constrained in the same way as those within the “body” of the material, so their motion is different

5. Direction of Vibration
In some mechanical waves, the particles/atoms move “back-and-forth” parallel to the direction of wave travel
these waves are called longitudinal or compressional waves
the “back-and-forth” particle motion alternately squeezes and stretches the medium
this creates regions in the medium that have
“higher than normal” density – called compressions
“lower than normal density – called rarefactions

6. Direction of Vibration
In some mechanical waves, the particles/atoms move “up-and-down” or “side-to-side” at right angles to the direction of wave travel
these waves are called transverse or shear waves
the “up-and-down” or “side-to-side” particle motion produces a waveform that has traditional crests and troughs
ALL electromagnetic waves are transverse waves
the electrostatic and magnetic fields both vibrate at right angles to the direction of wave travel

7. Direction of Vibration
In some mechanical waves, the particles/atoms move in a combination of “back-and-forth” and “up-and-down” that results in a circular path
this motion can only happen at the boundary between two media with different properties
thus, a circular particle motion path occurs in surface waves
surface waveforms have traditional crests and troughs

8. Wave Diagrams
Longitudinal and transverse waves

9. Wave Diagrams
Surface wave (water wave)

10. Wave Diagrams
Electromagnetic waves