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PHYS270

  • L2-25: LIGHT BULB IN WATER

    L2-25
    Do a magic trick using partially reflected light.
    Light from a light bulb located in the front (enclosed) part of the box is reflected off a glass plate such that the reflection (and thus the lit bulb) appears to be in a beaker of water.

  • L2-27: Infinity Mirror - Portable

    L2-27
    Illusion with half-silvered mirror.

    This is a smaller, more easily portable version of demonstration L2-22, suitable for use in small classrooms. A ring of lights is repeatedly reflected by a rear mirror and a partially silvered front window, creating the illusion of lights vanishing into the distance.
    L2

    L2-27: mirror device illuminated on table, showing shallow housing for lights behind mirrored face

  • L2-61: MIRROR TILES WITH LIGHT BULB

    L2-61
    Show multiple reflections using two mirrors
    Two hinged mirror tiles are positioned at an acute angle with a single light bulb between them. The succession of images makes it appear that there are many more bulbs, with the exact number dependent on the angle between the two mirror tiles.

    geo

  • L2-62: MULTIPLE REFLECTIONS WITH MIRROR TILES

    L2-62
    Show multiple reflections in a three-dimensional system of mirrors.
    A corner reflector is formed using three orthogonal mirror tiles.

  • L3-01: OPTICAL BOARD - CONVEX SPHERICAL MIRROR

    L3-01
    Show reflection of light rays from a convex mirror.
    Parallel rays incident on a spherical convex mirror appear to diverge from the focal point of the mirror as the apparent source. Use a convex lens to obtain parallel rays. Choice of baffle and distance of baffle from source determine the number of rays and their spacing.
    FS0

  • L3-03 LARGE CONVEX MIRROR (60cm)

    L3-03
    Shows the image from a convex mirror
    Just observe your image in the mirror. Note that this type of mirror is used in stores, school buses, and other commercial applications. Because it produces an erect and small image, it can be used as the right hand rear view mirror in a car to see over several lanes of traffic. Because the image is smaller and therefore looks farther away, rear view mirrors carry the warning "Objects in this mirror are closer than they appear."
    OS8

  • L3-11: OPTICAL BOARD - CONCAVE SPHERICAL MIRROR

    L3-11
    Illustrate reflection from a concave spherical mirror.
    A series of parallel rays are formed using a slit baffle and with concave and convex lenses. These rays are incident onto a concave spherical mirror, which focuses them to a point with some spherical aberration, as can be seen in the photograph. Number and spacing of rays are adjustable by choice of baffle and position of baffle. A baffle with sets of rays of different color can be used to draw attention to the different aberration of different sets of rays.
    FS0

    l3-11a

  • L3-16 FOCUSING OF HEAT WAVES BY MIRRORS

    L3-16
    Demonstrates that concave mirrors can focus heat waves
    Two parabolic concave mirrors are used to focus heat from a nichrome heater and light a match.
    L3, PW1

  • L3-31 GIANT 160cm MIRROR - CONCAVE AND CONVEX

    L3-31
    Demonstrates images from concave and convex mirrors
    This five-foot diameter, 132cm (252-inch) radius of curvature parabolic mirror was originally designed as a solar collector on a satellite. Both convex and concave sides can be used with large classes or individually.

    Students can stand in front of the concave side at different distances to find the focal point. Invite students to predict the orientation of the image they see at different points, then try it out.
    FS0

  • L3-33: VANITY MIRROR

    L3-33
    Show the image produced by a cocave mirror.
    A standard hand-held vanity or shaving mirror, flat on one side, concave on the other. Pass it around for the class to examine, or simply use it to admire yourself.

  • L4-01 OPTICAL BOARD - RECTANGULAR SLAB

    L4-01
    Demonstrates refraction. Shows displacement of rays in a uniform slab of glass
    A slit baffle with concave and convex mirrors are used to produce a beam of parallel rays of light. A rectangular slab of lucite placed at an angle in the rays of light produces refraction at each surface, leading to displacement of the light rays. The central ray in the picture is reflected internally off the end surface of the slab and directed upward.
    FS0

  • L4-04: REFRACTION - CAN IN WATER TANK

    L4-04
    Illustrate refraction
    The can rests halfway into a water bath. Viewed at an angle, the can appears discontinuous at the water surface. The wimps who can't explain the neat picture at the left can go with the more classic view at the right.
    L4

    l4-04a

  • L4-23 BENDING OF LASER BEAM IN SUGAR SOLUTION

    L4-23
    Demonstrates a medium with a continually varying index of refraction
    Placing sugar along the bottom of a long, narrow water tank, as the sugar dissolves it creates an index of refraction gradient with the greater index of refraction nearer the bottom of the tank. A laser beam bends continuously in the sugar solution and reflects off the bottom of the tank, as shown in the photograph. Observation of the path of the laser beam is enhanced by adding a pinch of powdered coffee creamer.

    Geometrical Optics

  • L5-01: OPTICAL BOARD - TOTAL INTERNAL REFLECTION

    L5-01
    Demonstrate total internal reflection and the critical angle.

    Rotate the semicircular slab of plexiglass with the light ray entering and exiting through the curved surface. Starting with the ray incident nearly perpendicular to the flat internal surface, rotate the semicircular slab until the critical point is reached and total internal reflection is obtained. Reflection at entrance can be avoided by having the light enter perpendicular to the surface. A single slit baffle and convex lens are used to produce a narrow ray of light.

    The Brewster angle can also be demonstrated by rotating the semicircular slab so that the transmitted refracted ray and the internally reflected ray are perpendicular. See Demonstration M7-11: OPTICAL BOARD - BREWSTER'S ANGLE.
    FS0

    l5-01a

    l5-01b

  • L5-02: TOTAL INTERNAL REFLECTION IN LONG TANK

    L5-02
    Demonstrate total internal reflection of a laser light.
    The laser light enters the end of the water tank and undergoes a series of internal reflections from the top surface of the water and the bottom of the tank.
    L5, LS1

  • L5-11 LASER WATERFALL

    L5-11
    Demonstrates total internal reflection of a laser beam in a water jet

    A clear plastic tank with a plugged spout is elevated above a second, shallower tank. The upper tank is filled with water. A laser is aligned so that it passes through the upper tank and is centered on the spout.

    When the spout is unplugged, the water streams out into the lower tank. Several internal reflections of the laser beam should be visible in the outgoing stream of water, down to the point where it becomes too turbulent to see clearly.

    As the water level in the tank drops, the water flow becomes so slow that the stream bends too sharply and there is no internal reflection, and the laser beam ceases to follow the flow of water.

    Background:

    The laser here is illustrating internal reflection: depending on the index of refraction of the water and the angle the light hits it at, more light can be reflected back and forth within the stream of water than passes through it. At a certain point, it exhibits total internal reflection, where essentially all of the light is traveling along the stream rather than heading straight out the side.

    This demonstration can beneficially be used in combination with demonstrations of fibreoptic technology such as L5-13 or L5-23.
    OS2, LS1

  • L5-12 PLEXIGLASS SPIRAL

    L5-12
    Demonstrates total internal reflection
    Due to total internal reflection the light from the lamp remains mostly confined within the spiral plexiglass rod, and only exits at the end, where the angle between the surface and the incoming light exceeds the critical angle

  • L5-14: LASER AND PLEXIGLASS TUBE

    L5-14
    Demonstrates total internal reflection
    The laser beam enters the plastic tube at a cutout along the top edge, and follows around the tube while spiralling downward

  • L5-23 FIBER OPTICS TREE

    L5-23
    Demonstrates total internal reflection
    An array of optical fibers is mounted above a light source with coloured filters. The light is guided along the fibers by total internal reflection, creating an attractive display.
    L5

    Geometrical Optics

  • L6-01: OPTICAL BOARD - CONVERGING SPHERICAL LENS

    L6-01
    Show focusing of a spherical (cylindrical) convex lens.
    Parallel rays incident on an 18 inch long convex cylindrical lens converge at the focal point of the lens. For a large aperture the spherical aberration is clearly seen, and chromatic aberration can be seen by blocking part of an extreme ray. Number of slits, and their color and spacing, can be changed by choice of slit baffle and distance of baffle from source.