Basic Principles of Waves

Image source: http://www.bbc.co.uk/bitesize/higher/physics/radiation/waves/revision/1/

Introduction to Waves
All waves have the following:

• Wavelength (Metres, m) – the distance from one peak to the next
• Frequency (Hertz, Hz) – how many complete waves there are per second, passing a specified point
• Speed (Metres per Second, m/s) – how fast the wave is travelling
• Amplitude – the height of the wave, from the mid-line to the peak

Waves transfer energy and information, without transferring matter.

Formulas for Waves

1. Speed = Frequency x Wavelength
2. Wave Speed = Distance / Time

Types of Waves

In transverse waves, the vibrations are at 90 degrees to the direction of travel of the wave. Most waves are transverse, including: electromagnetic (EM) waves and S-waves.

In longitudinal waves, the vibrations are along the same direction as the wave is travelling. Examples include sound, ultrasound, P-waves and the slinky example when pushing and pulling the end.

Note: longitudinal waves are presented as transverse on an oscilloscope – representing longitudinal waves on paper is very difficult!