*DIFFRACTION*

I. When light waves pass through a narrow slit or opening the shadow regions are not sharp at the edges.

A. By blocking part of the wave, interference can take place and the pattern that is produced is called

a *diffraction
pattern*.

B. For a rectangular slit opening, the location of the first minimum in the diffraction pattern as measured

from the center of the
central maximum is given in terms of the angular displacement *theta*

asin(*theta)* = lambda

where a is the slit width, and lambda is the wavelength.

C. How are phasors used to determine
the diffraction pattern intensity quantitatively?

D. What is Rayleigh's criterion?

II. How is diffraction combined with two slit interference to describe the resulting intensity pattern?

III. Diffraction Gratings

A. What is a diffraction grating and what is the grating equation that describes the positions of the maxima?

B. What is dispersion when it refers to a diffraction
grating?

C. What is the resolving power of a grating?