Previously, we studied differential equations in which the unknown function had one independent variable. A partial differential equation is an equation that involves an unknown function of more than one independent variable and one or more of its partial derivatives. Many important and interesting physical phenomena are modelled by the functions of several variables that satisfy certain partial differential equations.
In this chapter, we will learn a few particular partial differential equations that arise in physical sciences such as heat equation, Laplace equation etc. Furthermore, we will explore these partial differential equations in terms of polar, cylindrical and spherical coordinates.