State the huygens-fresnel principle. (b) what device is used to collect the data in this experiment? (c) plane waves are incident on a slit whose width is adjustable. the slit starts out on wavelength wide and increases to a width of 1000 wavelengths. describe qualitatively the change in the diffraction pattern.

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Explanation:

a.Huygens- Fresnel Principal:- States that every unobstructed point on the wave front acts, at a given instant,as a source of out going secondary spherical wave front. This principle is used to study the phenomenon of diffraction and refraction.

b.Photo voltaic cells that converts light falling it into current or voltage and the experiment is single slit diffraction experiment.

c. On  increasing the slit width, the central maximum width gets narrower. The smaller the object the wave interacts with, the more spread there is in the interference pattern. Whereas increasing the size of the opening reduces the spread in the pattern.