4.3a An oscillating system produces waves. The nature of the system determines the
type of wave produced.
4.3b Waves carry energy and information without transferring mass.This energy may
be carried by pulses or periodic waves.
4.3c The model of a wave incorporates the characteristics of amplitude, wavelength,*
frequency*,period*, wave speed*, and phase.
4.3d Mechanical waves require a material medium through which to travel.
4.3e Waves are categorized by the direction in which particles in a medium vibrate
about an equilibrium position relative to the direction of propagation of the wave,such
as transverse and longitudinal waves.
4.3f Resonance occurs when energy is transferred to a system at its natural frequency.
4.3g Electromagnetic radiation exhibits wave characteristics.Electromagnetic waves
can propagate through a vacuum.
4.3h When a wave strikes a boundary between two media,reflection*, transmission,
and absorption occur. A transmitted wave may be refracted.
4.3i When a wave moves from one medium into another, the wave may refract due to a
change in speed. The angle of refraction (measured with respect to the normal) depends
on the angle of incidence and the properties of the media (indices of refraction).*
4.3j The absolute index of refraction is inversely proportional to the speed of a wave.*
4.3k All frequencies of electromagnetic radiation travel at the same speed in a vacuum.*
4.3l Diffraction occurs when waves pass by obstacles or through openings. The wave-
length of the incident wave and the size of the obstacle or opening affect how the wave
4.3m When waves of a similar nature meet, the resulting interference may be explained
using the Principle of Superposition. Standing waves are a special case of interference.
4.3n When a wave source and an observer are in relative motion, the observed fre-
quency of the waves traveling between them is shifted (Doppler effect).