Introduction to Waves

Displacement

The distance and direction of a vibrating particle from its equilibrium position

Amplitude

The maximum displacement of a vibrating particle

Wavelength

The distance for one complete cycle in a wave

OR

The distance from any point on one wave to the same point on the next wave along

Frequency

The number of complete cycles passing a certain point in 1 second

Period

The time for one complete wave to pass a fixed point

What do waves do?

Transfer energy and information but without transferring matter

How do waves transfer energy?

Through oscillations in the material which the wave is travelling through

Mechanical waves

Waves that pass through a material are vibrations of that material

Examples of mechanical waves

Sound waves, seismic waves, strings

Electromagnetic waves

Vibrating electrical or magnetic fields through space (no material needed)

Examples of electromagnetic waves

The electromagnetic spectrum, e.g.:

• Radio waves

• Microwaves

• IR

• Visible light

• UV

• X-rays

• Gamma rays

Longitudinal waves

Particle oscillation is parallel to the direction of energy transfer

What do longitudinal waves travel in?

They travel in a series of compressions and rarefactions

Transverse waves

Particle oscillation is perpendicular to the direction of energy travel

Peak

Positive displacement

Trough

Negative displacement

What does the x-axis represent on a transverse wave diagram?

Equilibrium position

Progressive waves

Transfer energy without transferring material, and is made up of particles of a medium (or field) oscillating