Investigating the various phenomena which occur when monochromatic light undergoes diffraction
Title: Determine the wavelength of a monochromatic light source (laser). Measure the groove spacing of a CD and the diameter of powder spores using diffractive methods.
Aim: The aims of this experiment are to determine the wavelength of the monochromatic light source and to determine the groove spacing of a CD and the diameter of the Lycopodium powder.
There are three parts to this experiment in the first part a diffraction grating is used to diffract light from a laser (monochromatic source of light). By measuring the angles of diffraction and by calculating the grating spacing, the wavelength of the light may be calculated. The light source used in the experiment should be a monochromatic light source as the experiment requires light of a single wavelength in order for the wavelength to be calculated. The second part of the experiment demonstrates how to determine the measurement of the groove spacing of a CD. The CD is used as a reflective grating; the light is reflected from the surface of the cd some of the reflected angles will give rise to constructive maxima, similar to a diffraction grating. The last part of the experiment is to determine the measurement of the diameter of powder spores by passing a monochromatic light source through a circular aperture and producing a diffraction pattern of concentric rings.
A diffraction grating consists of a series of opaque and transparent strips. Light passing through the grating is broken up into portions which come through each slit. The light from the various slits interfere with one another producing dark and bright fringes. Bright fringes occur when the path length of the light from adjacent slits to the screen is an integral multiple of the wavelength. These bright fringes or constructive interference are given by:
d = distance between consecutive slits on the...