moving in one dimension along the 
-axis subject to a restoring force 
a damping force 
and a driving force 
so that its displacement from equilibrium, at time 
satisfies the equation of motion:
is: an oscillating system that is supplied with energy (continuously or periodically) by an externally applied driving force.
is exemplified: by a mechanical oscillator consisting of a particle of mass moving in one dimension along the -axis subject to a restoring force a damping force and a driving force so that its displacement from equilibrium, at time satisfies the equation of motion:
and consequently will eventually exhibit forced oscillations described by
where 
and 
with 
and 
[P5.2, P5.3]
is also exemplified: by an electrical oscillator consisting of an inductance 
in series with a capacitance 
and a resistance 
driven by an applied voltage 
In such a system the charge 
stored on the capacitor at time is described by the same equations as the driven mechanical oscillator, subject to the replacement of 
and 
by 
and 
respectively. [P5.4]
has angular frequency: 
which is completely independent of the natural frequency 
of the oscillating system in the absence of driving or damping forces. [P5.4]
displays amplitude: 
which is generally dependent on the angular frequency 
of the driver and which may exhibit resonance at a particular driving frequency. [P5.4]
Copyright 1997, The Open University