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Single-Slit and Diffraction

Single-slit is set to its maximum width.

It is placed it in the path of the laser beam with the slit vertical and positioned so that the laser spot on the screen is as bright as possible.

Compare the size and shape of the spot that would appear on the screen with that seen without the slit.

The width of the slit is slowly decreased. Once diffraction effects become evident, what happens as the slit gets narrower?

Why is there no change in the pattern in the vertical direction? What do you suppose the pattern for a round hole would look like?

Solution Preview

The diffraction pattern exhibits a series of bright spots (maxima) perpendicular to the orientation of the slit (it will align with the direction of the width)

To see a diffraction pattern the laser wavelength should be about the same order of magnitude as the slit width.

The location of the maxima of order m is given by:

y = (m * L * D) / a


m is the diffraction order (from zero to infinity)
L is the wavelength
D is the distance to the screen
a is the width of the slit

So we ...

Solution Summary

Single-slit and diffraction are discussed.