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1 - Mechanics 2 - Fluid Mechanics 3 - Oscillations and Waves 4 - Thermodynamics 5 - Electricity and Magnetism 6 - Optics 7 - Modern Physics
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6 - Optics

Geometrical Optics
Photometry
Diffraction
Interference
Color
Polarization
The Eye
Modern Optics

6A - Geometrical Optics

6A2 - Straight Line Propagation

Light and Siren in Vacuum (6A02.10)
A buzzer and a LED are mounted inside a bell jar. The air is then evacuated from the jar, and although the LED can still be seen, no sound can be heard from the siren. Also listed as 3B30.30.

Straight Line Propagation (6A02.15)
Cast shadows from a point source or illuminate a laser beam with a cloud of chalk dust.

6A10 - Reflection from Flat Surfaces

Optics Board - Plane Mirrors (6A10.10)
Plane mirrors on the optics board.

Angle of Incidence and Reflection (6A10.11)
A beam of white light hits on a mirror mounted on a large rotating protractor. Angles of incidence and reflection can be compared by rotating the mirror.

Microwave Reflection (6A10.18)
Reflect microwaves off a metal plate into the receiver.

Diffuse and Specular Reflection (6A10.20)
Reflect a laser off a rough surface to show diffuse reflection. Compare with a mirror, polished metal surface, etc.

Corner Reflector (6A10.30)
Three mirrors joined to form the corner of a retroreflective cube; the incident and reflected rays will be parallel. Used in safety reflectors and have been left on the moon for precise distance measurements.

Parity Reversal (6A10.37)
Two ball and stick figures of Cartesian coordinate systems, but with opposite handedness. Used with a plane mirror to show parity reversal of reflected images.

Hinged Mirrors (Multiple Reflections) (6A10.40)
Two plane mirrors are joined by a hinge and can be adjusted to various angles between them. A small light bulb mounted between the mirrors is the object, and the number and positions of its images are noted as the angle between the mirrors changes.

Parallel Mirrors (Barbershop Mirror Effect) (6A10.45)
Two plane mirrors are placed parallel to and facing one another. An object is placed between them and multiple images are seen in the view past the edges of the front mirror.

Location of Image (Candle in a Glass of Water) (6A10.60)
A vertical glass window pane stands between two objects - a candle in front and a beaker of water in the rear at the position of the candle's image in the glass. The image of the candle appears to be burning under water.

6A20 - Reflection from Curved Surfaces

Optics Board - Curved Mirrors (6A20.10)
Concave and convex mirrors on the optics board.

Large Concave Mirror - Strawberries (6A20.31)
Real image of plastic strawberries when placed at the center of curvature and aligned with the optical axis.

Large Concave Mirror - Candle Burning at Both Ends
A burning candle is placed at the center of curvature, but slightly above the optical axis. The reflected image is upside down so the candle looks like it is burning at both ends.

Large Concave Mirror - One Candle Searchlight
A burning candle placed at the focal point produces a large image of the candle flame when projected across the room.

6A40 - Refractive Index

Broken glass in Oil (6A40.30)
Status: Unavailable
Broken glass will disappear in mineral oil because they have near identical indicies of refraction. Tip the container to see the effect.

Mirage with a Laser (6A40.47)
A laser beam almost grazing a hot surface will show deflection.

Schlieren Optics System (6A40.60)
Variations in the refractive index of the air in front of a spherical mirror are visible in a schlieren optics setup. See Standing Longitudinal Waves and Ultrasonic Levitation (3B22.60)

6A42 - Refraction from Flat Surfaces

Optics Board - Reflection and Refraction from Plastic Block (6A42.10)
A large rectangular acrylic block on the optics board will refract and partially reflect incident beams. Can be rotated to various angles to vary the angle of incidence refraction.

Bent Stick in Water (6A42.45)
A stick appears bent or broken when inserted into water at an angle.

Acrylic and Lead Glass Refraction (6A42.47)
Hold a stick behind a block of acrylic (n=1.4) and lead glass (n=2). At each interface (air to acrylic, and acrylic to lead glass), the image of the stick is shifted when viewed off the normal to the surface of the blocks.

6A44 - Total Internal Reflection

Critical Angle and Total Internal Reflection (6A44.20)
A beam of light traveling underwater is reflected up to the water/air interface by a small mirror. The mirror may be rotated to change the angle of incidence. Fluoroscein in the water and a thread screen above the water allow the incident, refracted, and reflected beams to be seen clearly. As the angle of incidence reaches the critical angle, the refracted beam is seen to skim just over the surface of the water. Increase the angle slightly from that, and the refracted beam disappears while the reflected beam jumps in intensity (total internal reflection).

Light Pipes and Fiber Optics (6A44.40)
White light or laser beams through straight and curved lucite rods, or various optical fibers.

6A46 - Rainbow

Optics Board - Rainbow (6A46.20)
Using a single beam of white light and large acrylic disc on the optics board.

6A60 - Thin Lens

Optics Board - Lenses (6A60.20)
Concave and convex lenses on the optics board.

Image Formation and Conjugate Focal Points (6A60.30)
Light from a backlit object is focused by a convex lens onto a translucent screen; shows image reversal and magnification. Can show that the lens can be placed at two conjugate locations; either one focal length away from the object or from the screen.

Magnification (6A60.35)
A backlit grid and a large 12 in. lens are used to demonstrate magnification by biconvex lenses. See also Fresnel Lens Magnification (6A65.70).

6A61 - Pinhole

Pinhole Camera (Camera Obscura) (6A61.20)
Large pinhole camera projects the image of a lamp filament onto a translucent screen. Has an adjustable iris and an optional focusing lens.

6A65 - Thick Lens

Chromatic Aberration and Achromatic Pair (6A65.21)
A bright source of white light is focused through a single lens showing different focal lengths for different wavelengths. The single lens is replaced with a two lens set that corrects the aberration. An achromatic pair (two lenses cemented together) is also shown.

Spherical Aberration (6A65.40)
Uses the Image Formation (6A60.30) setup, but with a large plano-convex lens. First the outer ring of the lens is blocked off, and an image is brought into focus. Then an inner disc is blocked off, and the image is seen to be out of focus but can be refocused by moving the lens.

Fillable Air Lenses (6A65.52)
Hollow lenses held underwater to show the refraction from water to air to water; the reverse of an air to glass to air path. The biconcave lens will focus the light and a biconvex lens will diverge the light. The lenses are then filled with water and the light passes through without any effect.

Glass Lenses in Air and Water
A glass lens is inserted in the thread screen to show the focal length in air, then is dipped into the optics tank to show a much longer focal length in water due to the smaller difference in the refractive indicies (glass/water vs glass/air).

Cylindrical Lens
Shows properties of a cylindrical lens.

Fresnel Lens Magnification (6A65.70)
Magnification (6A60.35) using a large plastic Fresnel lens.

6A70 - Optical Instruments

Microscope Model (6A70.10)
A simple model of a microscope. Note: This works quite well with the Telescope Models (6A70.20).

Projection Microscope
A projection microscope magnifies and projects the grid from a fine wire mesh screen.

Telescope Models (6A70.20)
Choose any or all of the types listed below. We use an eye chart for the object, and small cameras for class viewing.

Telescope Models - Galilean (Non-inverting)
Uses a converging objective lens and a diverging eyepiece lens to produce a non-inverted image.

Telescope Models - Keplerian (Inverting)
Uses two converging lenses to produce an inverted image (but with a wider field of view and greater magnification).

Telescope Models - Newtonian (Reflecting)
Status: Unavailable
Note: Currently being rebuilt.

6B - Photometry

6B10 - Luminosity

Light Meters
Electronic photometers, one with digital and one with analog output.

6B40 - Blackbodies

Bichsel Boxes (6B40.20)
Two 3x5 index card boxes each with a small hole in the lid; one is painted black inside and the other white. Hold the boxes up to the students with the holes facing them and they appear almost identical. Open the lids and the difference is obvious. Useful in discussing blackbody cavity radiation.

Blackbody Radiator (6B40.26)
A piece of carbon has a narrow hole drilled in the side. As viewed with a video camera, the hole appears darker than the surrounding metal. If the carbon is heated with a gas torch to a high enough temperature, the hole will glow brighter than the surrounding metal.

Infrared in the Spectrum (6B40.41)
Status: Unavailable
Light from a hot carbon arc lamp is spread into a spectrum, then various portions of the spectrum are scanned with a thermopile and galvanometer. It is shown that the greatest amount of energy is in the infrared portion of the spectrum where no visible light exists, then tapers off into the visible and disappears in the ultraviolet. Note: This is done on the same setup as Ultraviolet in the Spectrum (7B13.40).

Radiation Spectrum of a Hot Filament (6B40.55)
Light from a variac controlled slide projector powered is spread into a spectrum by a diffraction grating. With the variac at a low setting the projector bulb is mildly warm and the spectrum consists of red light only. Turn the variac up slowly, and as the temperature of the bulb increases the spectrum comes to include orange, yellow, green, and (at white heat) blue light.

6C - Diffraction

6C10 - Diffraction Through One Slit

Laser and Single Slit (6C10.10)
A laser beam passes through a slide with four single slits of known widths.

Laser and Single Slit (Cornell Slide) (6C10.12)
The Cornell slide has several single slits of various widths as well as a gradually widening slit.

Laser and Adjustable Single Slit (6C10.15)
A variable width single slit shows diffraction of a laser beam.

Microwave Single Slit Diffraction (6C10.50)
Single slit diffraction of microwaves.

6C20 - Diffraction Around Objects

Arago's (or Poisson's) Bright Spot (6C20.10)
Light from a laser is diffracted around a small ball bearing. This is on the same table as Point and Eye of a Needle (6C20.22) and Knife Edge Diffraction (6C20.15).

Knife Edge Diffraction (6C20.15)
Light from a laser is diffracted by a razor blade, also the elliptical cut out in the center of the blade.

Hair or Thin Wire (6C20.20)
Diffraction pattern from a strand of hair or a thin wire in a laser beam.

Point and Eye of a Needle (6C20.22)
Light from a laser is diffracted by the point and eye of a needle.

Aperture Diffraction (Airy Disk) (6C20.30)
Circular diffraction pattern from passing a laser beam through a small aperture.

Diffraction from a Feather (6C20.62)
A laser beam passing through the closely spaced hairs of a feather will spread into a diffraction pattern.

Note:
Optical Analog of X-ray Diffraction from DNA (7A60.25) is in Section 7A: X-ray and Electron Diffraction.

6D - Interference

6D10 - Interference From Two Sources

Laser and Double Slits (6D10.10)
A laser passes through a slide with four double slit combinations (two different slit widths and two spacings).

Laser and Double Slits (Cornell Slide) (6D10.11)
The Cornell slide has various double slits as well as a gradually widening double slit.

Microwave Double Slit Interference (6D10.20)
Three double slit spacings for the microwave apparatus.

Fresnel Biprism (6D10.41)
Look for this in the optics room.

6D20 - Gratings

Laser and Multiple Slits (6D20.10)
A laser passes through a slide with 2, 3, 4, and 5 slits.

Laser and Multiple Slit Interference (Cornell Slide) (6D20.10)
The Cornell slide has five sets of multiple slits.

Transmission Gratings with White Light and Lasers (6D20.20)
White light and two lasers (one red, one green) are passed through four diffraction gratings of various line densities. The white light produces a continuous spectrum and the two lasers produce different diffraction patterns.

Two Dimensional Gratings (6D20.35)
Very fine wire mesh slides (100 to 3,000 lines per inch) and a laser produce two dimensional patterns.

Crossed Gratings and a Laser (6D20.50)
A pair of linear diffraction gratings at right angles produces a two dimensional pattern.

Point Source and Wire Mesh (6D20.55)
A point source of white light is viewed through small pieces of wire mesh handed out to the students. The weave of the mesh is fine enough to diffract the light.

Reflection Gratings
Concave reflection gratings can simultaneously disperse and focus white light.

6D30 - Thin Films

Newton's Rings (6D30.10)
White light interference pattern from a thin layer of air between two layers of glass; one flat and the other slightly curved.

Soap Film Interference (6D30.20)
White light is reflected off a thin soap film onto the screen. Dazzling multicolor interference patterns are formed, with rough bands of different colors indicating the varying thickness of the film. Eventually a dark area forms at the top (where the film is less than a quarter wavelength thick), spreads down throughout the pattern, and the film pops.

Glass Plates in Sodium Light (6D30.30)
Two large flat glass plates are stacked and illuminated by a sodium lamp. The yellow and black interference fringes are easily visible to the entire class.

Pohl's Mica Sheet (6D30.40)
Violet light from a mercury lamp is reflected from a thin sheet of mica onto the screen, producing a circular interference pattern.

Interference Filters (Dichroic Filters) (6D30.60)
Glass slides with precise thin film coatings produce constructive interference for a specific wavelength which gets transmitted through the filter. All other wavelengths get reflected.

6D40 - Interferometers

Michelson Interferometer - Laser (6D40.10)
Michelson interferometer with a laser.

Michelson Interferometer - Microwaves (6D40.20)
Interference maxima and minima from microwaves are detected as one of the "mirrors" is moved.

Mach-Zehnder Interferometer (6D40.32)
A large Mach-Zehnder Interferometer using a HeNe laser. Please give us at least two days notice.

Fabry-Perot Interferometer (6D40.55)
A simple interferometer but with poor mirrors (low finesse).

6F - Color

6F10 - Synthesis and Analysis of Color

Additive Color Mixing (6F10.10)
Red, green, and blue sources with individual brightness controls shows aspects of additive color mixing, primary and secondary colors, etc.

Color Filters (6F10.20)
Various color filters used with white light.

Subtractive Color Mixing (6F10.23)
Uses the same device as in Additive Color Mixing (6F10.10). Cyan, magenta, and yellow filters are used to produce red, green, and blue from white light.

Newton's Color Disk (6F10.25)
A disk sectioned into primary colors appears white when spun quickly.

Spinning Black and White Disc
An illusion of color from a spinning black and white disc due to the eye's different reaction speeds to different colors.

Recombined Spectrum (6F10.30)
A continuous spectrum from a prism is recombined into white light with a second prism.

Colors in Spectral Light (6F10.75)
Objects colored with fairly pure hues are moved through a white light spectrum to show reflectivity and apparent color in different colors of light.

Polaroid-Land Effect
Two black and white slides of the same image are projected so that they overlap on the front screen. A individual red filter is placed in front of one slide projector. The black and white image appears in full color. Note: Talk to us first for background information.

6F40 - Scattering

Rayleigh Scattering (Artificial Sunset) (6F40.10)
White light is scattered when passing through a water tank that also contains a precipitating solution of hypo (Sodium Thiosulfate) and sulfuric acid.

6H - Polarization

6H10 - Dichroic Polarization

Linear Polarization Model
A ball and stick model of linear polarization.

Polaroid Sheets (6H10.10)
12" x 12" sheets of Polaroid material for use on an overhead projector.

Polarization of Microwaves (6H10.20)
Polarized microwaves pass through a rotating metal grating; the orientation of the grating affects the transmitted intensity in the same way as crossing polaroid sheets.

6H20 - Polarization by Reflection

Polarization by Reflection (Brewster's Angle) (6H20.10)
White light from a bright lamp reflects off a glass plate and onto the front screen producing a focused image of the lamp filament. Insert a Polaroid sheet and rotate it to show that the reflected beam is polarized. Repeat with the beam shining straight onto the wall to show that the unreflected beam is not polarized. The angle of incidence can be changed to show that there is an optimum angle of reflection for maximum polarization of the beam.

Polarization by Double Reflection (6H20.20)
Two glass plates are mounted at Brewster's angle with the second able to rotate around the axis of the incident light.

6H30 - Circular Polarization

Circular Polarization Model
A ball and stick model of circular polarization.

Three Polaroid Sheets (6H30.10)
Two polaroid sheets (6H10.10) are placed on the overhead projector with their axes of polarization perpindicular to each other (no light passes through). A third polarizer is then placed in between the original two sheets and light will pass through.

Sugar Tube (6H30.40)
A beaker of corn syrup is placed on an overhead projector with a polaroid sheet above and below. The polarization plane of the linearly polarized light rotates in the corn syrup with different wavelengths rotating by different amounts. The top polaroid is an analyzer and rotating it will select which wavelength is projected onto the screen.

6H35 - Birefringence

Birefringence in Calcite (6H35.15)
A single point of white light passes through a calcite crystal, is doubly refracted, and is projected on the screen as two dots. Rotating a polaroid sheet above the crystal shows that the two transmitted dots have orthogonal polarizations. Rotating the crystal makes one dot revolve around the other (the ordinary and extraordinary rays).

Quarter Wave Plate (6H35.40)
Status: Unavailable
Come back to this.

Polarization by Stress in Plastic (6H35.50)
A piece of acrylic is squeezed between two polarizers. Uses an overhead projector for a light source.

6H50 - Polarization by Scattering

Polarization by Scattering (6H50.10)
White light passes through a polarizer, then is scattered by passage through a tank of water with a little milk as scattering centers. The polarized light is scattered preferentially in the direction of its polarization, and by rotating the polarizer the direction of most intense scattered light can be varied. A mirror above the tank allows simultaneous viewing of the top and front views for comparison of vertically and horizontally scattered light.

6J - The Eye

6J10 - The Eye

Human Eye Model (6J10.10)
A model of the human eye.

Resolving Power of the Eye (6J10.80)
A black screen with four double slit patterns is placed in front of a bright sodium lamp. The double slit patterns vary in separation and the class is asked in which pattern can they resolve both slits.

6J11 - Physiology

Color Blindness (6J11.70)
Color blindness slides are projected to test the class.

6Q - Modern Optics

6Q10 - Holography

Holograms (6Q10.10)
A variety of holograms using lasers and white light. Works best if you allow time for the class to look for themselves as cameras can be hard to align. Note: Please give us at least two days notice!