## Geometric Optics - Diffraction and Interference Rich Text Content

A. Single Slit

As the width of the single slit increases, describe how the intensity pattern changes:

As the width of the single slit increased, the width of the maxima/minima decreased, the distance between the maxima/minima decreased, and the intensity of the central maxima increased.

How does the intensity pattern change from a change of longer wavelength to shorter wavelength for a single slit?:

As the wavelength decreased, the central maxima became narrower, and the maxima/minima became closer together (i.e. the spacing decreased).

B. Double Slit

Compare the intensity pattern of the double slit to that of the single slit. Which features of the pattern result from single-slit diffraction and which from two-slit interference?:

The dropoff in intensity from the central maxima is a direct result from the diffraction of the single slit whereas the "dot" nature of the maxima/minima interference pattern is unique to the double-slit interference pattern. While the single slit has a diffraction pattern that looks diffuse across maxima/minima that may be stretched out, the double slit pattern has within these maxima stronger portions of intensity.

As the width of the double slit increases, describe how the intensity pattern changes:

As the width increases, the overall intensity increases since the distance between the maxima and minima decrease and the width of the maxima/minima decrease as well.

How does the intensity pattern change from a change of longer wavelength to shorter wavelength for a double slit?

As the wavelength decreases, the overall intensity increases, the maxima and minima become closer together, and their widths become smaller.

C. Diffraction Grating

Compare the intensity pattern of the diffraction grating to that of the double slit. Why is a multiple slit grating better than a two-slit grating for making accurate determination of wavelength?

There are far fewer maxima/minima than in the double slit experiment and they are a lot more pronounced and well-defined dot patterns. Diffraction gratings are better than two-slit gratings for making determinations of wavelength precisely because the maxima and minima become very far from each other making it easier to measure between the maxima.

As the spacing of the diffraction grating increases, describe how the intensity pattern changes:

As the spacing increases, the width of the maxima/minima decreases, and the overall intensity of the central maxima increases with an increased focus to the center.

How does the intensity pattern change from a longer wavelength to a shorter wavelength for a diffraction grating?

The distance between the maxima decreases and the overall intensity of the central maxima increases with an increased amount of focus.

D. Wavelength Determination

Calculate the wavelength of the red laser using the intensity pattern of the diffraction grating:     rich_text