This document describes the setup and components used to determine the wavelength of light using a Fresnel biprism, including an optical bench, biprism, convex lens, sodium vapor lamp, slit, and micrometer eyepiece. It also describes setups for determining the diameter of a wire using diffraction in the shadow region phenomenon and measuring the length of a rod to remove bench errors. The key components are identified as the biprism, which splits the light source into two virtual sources, and the relationship that the wavelength can be determined from measurements of the fringe width, distance between virtual sources, and distance from the slit to the eyepiece.