ABSTRACT
Complex numbers are used in many scientific fields, including engineering, electromagnetism, quantum physics and applied mathematics, such as chaos theory. Complex numbers are used in signal analysis and other fields for a convenient description for periodically varying signals. In fluid dynamics, complex functions are used to describe potential flow in two dimensions. There are several applications of complex numbers in science and engineering, in particular in electrical alternating current theory and in mechanical vector analysis This chapter explains two main forms of complex number – Cartesian form (named after Descartes) and polar form. A complex number may be represented pictorially on rectangular or Cartesian axes. Two complex numbers are added/subtracted by adding/ subtracting separately the two real parts and the two imaginary parts. Any physical motion which is periodic, such as an oscillating beam, string, wire, pendulum, electronic signal or electromagnetic wave can be represented by a complex number function.
