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#### Lab Activities

In this lab, the students experimentally confirm the validity of the following:

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:

Iq = Imax[ (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:

Iq = Imaxcos 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:

Iq = (Imax/N2) [(sin Nb)/sin b]2 [(sin a)/a]2

where N is the number of slits.

Some writeups include demonstations for the following:

Crossed polarizers
Brewster angle
Rotation of plane of polarization
Newton's fringes
Dispersion of light

#### Course Level

Introductory: P4, P14, P16

#### Equipment

Number of set-ups available: 20

Per lab station:

1 30 V DC power supply/wooden stand
1 X-Y recorder/plotter pen and 10 ohm resister across Y inputs
1 HeNe laser/wooden stands
1 ring stand/metal platform
1 slit plate/holder
1 mounted photoresistor
1 2m meterstick
2 flat mirrors/optical bench mounts
1 slide with .005" wire mounted on it
2 wooden wedges
1 flashlight
1 T-ruler
1 slit plate dimensions sheet taped to table

#### Demos 1-3: Crossed Polarizers, Brewsters Angle, Rotation of plane of Polarization

2 polarizers
1 holographic diffraction grating
1 bottle of corn syrup
1 800 ml beaker filled with water

#### Demo 4: Newton's Fringes

1 sodium lamp
1 thin glass slide

#### Demo 5: Dispersion of Light

1 plastic square container filled with water
1 flashlight
coffee creamer

#### Notes

 Last Update: Site contact: largent@Dartmouth.EDU