Physics

[latexpage]

# General notes:

• A hallmark property of waves is interference
• In physics, waves are usually associated with the transmission of enegry between different points in space

# Three Types of Waves

1. Mechanical waves
2. Electromagnetic waves
3. Matter waves

## Mechanical waves

Mechanical waves are propagations of a disturbance thorugh a material medium due to periodic motion of particles that comprise the medium from their mean positions

• Existence of a medium is essential for propagation of a mechanical wave
• Propagation occurs due to properties of the medium such as elasticity and inertia
• Energy and momentum propagate via motion of particles in the medium BUT the overall medium remains in its original position
• Two main types of mechanical waves:
1. Transverse waves = the vibration of particles in the medium occurs perpendicular to the direction of wave propagation (e.g., vibration on a string)
2. Longitudinal waves = the vibration of particles in the medium occurs parallel to the direction of wave propagation (e.g., oscillations in a spring, internal water waves, tsunamis, sound waves etc.)

## Electromagnetic waves

Electromagnetic waves = periodic distortions in electric and magnetic fields

• Two components: an electric component and a magnetic component
• Initiated when charged particles (e.g., electrons) begin vibrating due to various forces acting on them
• The vibration of these charged particles then results in the emission of energy called electromagnetic radiation
• Importantly, electromagnetic waves do NOT require a medium to travel through
• As far as we know, this property is unique to electromagnetic waves
• Other properties:
• Travel at the speed of light ($3 \cdot 10^8 \mathrm{m/s}$) in a vacuum
• Can be polarized
• Transverse in nature
• Propagate out from their source (i.e., the vibrating particles)
• Oscillations of waves occur perpendicular to the direction they are propagating/traveling
• Furthermore, in the case of electromagnetic waves, oscillations in the magnetic component occur in a direction perpendicular to oscillations in the electric componet
• No medium required
• All EM waves have momentum (thus, they have kinetic energy)

## Matter waves

Matter waves (or, de Broglie waves) = depict the wave-like properties of all matter

• Assumes wave-particle duality for all matter
• Frequency of these waves depends on their kinetic energy
• Momentum is not directly (or, inversely) proportional to position of the wave

## Miscellaneously-classed waves

Surface waves (or, Rayleigh waves) = can have mechanical or electromagntic nature

Standing waves = a wave that remains constant

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