Relaxation oscillations are maintained by a constant external influence and present two diferent timescales (fast and slow). In a previous paper we emphasized the qualitative diferences between pendular and relaxation oscillations, showing some physical examples. In this paper we present the pioneering contribution given to this subject by the dutch physicist Balthazar Van der Pol, as well as some properties of the equation bearing his name, and which is one of the prototypes of nonlinear dynamical systems. We show applications of the Van der Pol equation in physics and biology.
relaxation oscillations; nonlinear oscillations; self-sustained oscillations
