1. For diffraction from a single slit:

a. the space between adjacent minima on either side of the central
maxima is given by the expression:

Dx = Ll/a

where L is the distance from the slit to the viewing screen, l
is the wavelength of the light and a is the width of the slit; and

b. the intensity of the light in the diffraction pattern as a
function of the angle q is given by the expression:

I_{q} = I_{max}[ (sin q)/q]^{2 }

where a = (p a q) /
l .

2. For interference and diffraction from a double slit:

a. the location of the maxima are given by the expression:

x = (nlL)/d

where n is the number of the maxima, l is the wavelength of the
light, L is the distance from the slit to the viewing screen and d
is the slit spacing; and

b. the intensity of the light in the interference and diffraction
pattern as a function of the angle q is given by the expression:

I_{q} = I_{max}cos ^{2} b

where b = (p d q)/l .

3. For a multiple slit system:

a. the maxima and minima locations for the envelope are due to
diffraction effects and are described mathematically by the appropriate
equations above; and

b. the intensity of the light in the interference and diffraction
pattern as a function of the angle q is given by the expression:

I_{q} = (I_{max}/N^{2}) [(sin Nb)/sin b]^{2} [(sin a)/a]^{2}

where N is the number of slits.