ABSTRACT
This chapter introduces the concept of a function, and proportionality and linear equations. It shows how linear equations can be represented by straight-line graphs. The simplest form of relationship between two quantities is linear. Linear relationships are found throughout science and have many applications. A function is a mathematical rule which defines the process by which an input is converted to an output. To define a function we need to know what the function does, but we also need to know what group of inputs it will act on. The group of all possible inputs is termed the domain. The Beer-Lambert law is a combination of the fundamental principles of absorption spectroscopy. It is based on the principle that certain compounds will absorb light of a given wavelength and that the level of absorption is directly proportional to concentration of material present.
