Magneto Optical Kerr effects are generally described macroscopically by dielectric tensor theory [Zak et al (1990)], or the effects can also be described microscopically, where the coupling between the electric field of the light and the magnetisation occurs by the spin-orbit interaction [Daalderop et al (1988)]. In the present work the effects are described less formally, in a pictorial fashion, using the idea of a Lorentz force. To understand the magneto optical Kerr effects, one needs to understand the terminologies associated with the effect, how the state of polarisation of reflected light is dependent upon the initial polarisation and the magneto optical geometry in which it is being used.Light is a transverse electromagnetic wave which can be manipulated optically into plane, circularly or elliptically polarised light (Fig. 2.1). Generally, the plane of polarisation is the plane which contains the electric field E and the direction of propagation. However in some texts [Corson & Lorrain (1970)], the definition of plane of polarisation refers to the plane containing the B field. Any reference to the plane of polarisation in the present work will assume the former definition. If the electric field is polarised in the plane of incidence, it is referred to as p-polarised light as shown in Figure 2.2. Conversely, if the electric field is polarised perpendicular to the plane of incidence, then it is referred to as s-polarised light. The plane of incidence is also known as the scattering plane - the plane which contains the