Intro to Waves

• a wave is defined as - the transfer of energy without the transfer of matter, also known as wave motion

• there are 2 types of waves that can transfer energy:

  1. transverse - particle vibrate at right angles to the direction of the wave, for example ocean waves

  2. longitudinal - particles vibrate in the same direction as the wave motion, but backwards and forwards, for example sound waves

• the number of waves produced a second is called the frequency

• there is no net change in transverse waves, and the wave travels away from its source

• period - time for one wave to pass through a fixed point

• wavelength - how long a wave is, measure peak to peak or trough to trough

• amplitude - the heights of the wave, and the displacement from the rest position

• frequency is measured in Hertz (Hz)

• 1 wave passing a point = 1 Hz

The Seven Qualities of a Transverse Wave

• wavelength (lambda)

• frequency (Hz)

• crest

• trough - max downward value

• amplitude - max upward value

• period

• wave speed

• Everything is made up of atoms - even air has atoms

• when one atoms bumps another, energy is transferred mechanically

• mechanical energy transfer - one atom bumps another

• vibration - a rapid continuous movement, creates sound waves

• longitudinal waves are sometimes called pressure waves

• longitudinal waves move to and fro in the direction of the energy flow

Calculating Wave Velocity

• period - time needed to complete a wavelength

• speed, frequency, and wavelength are linked by the wave equation

• if frequency increases, wavelength decreases, and vice versa

• wave equation - v = f λ

• v = speed of wave (m/s)

• f = frequency of wave (Hz)

• λ = wavelength of wave (m)

• to calculate frequency - f = v/λ

• to calculate wavelength - λ = v/f