In this experiment, we study the relationship between the intensity distribution and the geometrical configuration of a corresponding source. In particular, the intensity of light is studied in the cases when the source exhibits spherical, cylindrical and plane symmetry. Theory Consider a source of a certain vector physical quantity E, such as electric field, gravitational field, etc. Imagine the field lines emerging from the source (or disappearing into the "sink"). If one uses a "net" to fully enclose the source (or sink), then the number of field lines captured by the net is the same, regardless of its shape and size. This is true as long as the field lines always emerge from a source and terminate at a sink. Therefore the flux of the field lines passing through the net, which is known as a Gaussian surface, defined as E dA , 4 is independent of the shape and size of the Gaussian surface. Here the surface integral is over the entire net. This observation is particularly valuable if the geometry of the source (or sink) is of a particular symmetry. For example, if the source is a point then obviously its E-field is spherically symmetric