What it shows:

Linearly polarized light, propagating down a long glass tube filled with corn syrup, is made to rotate its direction of polarization by the optically active corn syrup. The intensity of the 90° scattered light varies dramatically, in a periodic manner, along the length of the tube -- the intensity being zero when the dipole radiators oscillate in the line of sight direction, and maximum intensity when they oscillate perpendicular to the line of sight. Scattered light is most intense when the electric field vector is perpendicular to the line of sight.

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What it shows:

Certain materials (sugar in this experiment) are optically active because the molecules themselves have a twist in them. When linearly polarized light passes through an optically active material, its direction of polarization is rotated. The angle of rotation depends on the thickness of the material and the wavelength of the light.

What it shows:

A linear polarizing filter followed by a quarter-wave plate whose slow and fast axes are at 45° to the axis of the polarizer becomes a circular polarizing filter, and incident unpolarized light emerges as circularly polarized light. This will not work if the order of the polarizer and wave plate is reversed. A quarter-wave plate converts circularly polarized light into linearly polarized light.

Simulation of atmospheric scattering and polarization of sunlight using slide projector and aquarium containing milky water.

What it shows:

When unpolarized light is reflected from a non-metallic surface, the reflected ray is plane polarized parallel to the reflecting surface if

θ_i + θ_r = 90°

or

tanθ_i = n

where θ_i = incident ray (Brewster's angle), θ_r = refracted ray, n = refractive index

How it works:

We use a black vinyl sheet 1m×4m as the reflecting surface, which has a Brewster angle of 57°. A theatrical spot lamp ¹ is used to give a 50cm circle...

What it shows:

The criterion for the resolution of two sources is that the central maximum of the single slit interference pattern of one source falls on the first minimum of the pattern of the second source.

How it works:

Each laser beam passing through the slit will form a diffraction pattern on the screen. With the aperture closed down, the pattern will be spread out and the central maxima of both sources will overlap giving a blurry image. Opening up the aperture and the diffraction patterns will get narrower, until the point...

Circular aperture effect.

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What it shows:

A point light source will produce seemingly sharp shadows which turn out to be not at all sharp when viewed under magnification. Narrow interference bands are seen within the shadow of a straight edge while more complicated shapes yield more complicated interference bands and striations.

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What it shows:  A room-size laser interferometer with audio signal output. A standing wave is produced whenever a wave is reflected back on itself. A resonant cavity requires a second reflection so that the twice reflected wave has the opportunity to be in phase with the original wave. Here, laser light is reflected from a half-silvered mirror (mounted on a wall) so as to return to the laser and be reflected again by the laser. Movement of the wall by half a wavelength is sufficient to change the cavity formed between laser mirror and wall mirror from one resonant...

What it shows:

A device to measure distances to an accuracy of fractions of the wavelength of light, it also provided the critical experiment for the non-existence of the ether and for the constancy of the speed of light in all inertial frames.

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What it shows

Waves reflecting from two surfaces can interfere constructively and destructively. In this case it is light waves that are being reflected from the front and rear surfaces of thin soap or oil films. The interference produces a pattern of beautiful colors in white light, or dark and light bands in monochromatic light.

What it shows:

In quantum mechanics, it is possible for a particle to tunnel through a potential barrier because its wave function has a small but finite value in the classically forbidden region. Here we use FTIR as an optical analog of this quantum mechanical phenomenon.

How it works:

A 45°-90° prism will deflect a beam of light by total internal reflection. When two such prisms are sandwiched back-to-back and pressed together, the air-glass interface can be made to vanish and the beam then propagates onward undisturbed. This transition, from...

What it Shows

A beam of laser light can be trapped inside a stream of water by suffering total internal reflection—the aquatic equivalent of a fiber optic cable.

What it shows:

A simple qualitative demonstration of total internal reflection using a laser beam.

How it works:

Using a fish tank suitably doped with a scattering agent (see Setting it Up), a ray of light...

What it shows:

There are various types of mirages possible, the details depending on whether the hot air is above or below the cool air and how sharp the transition is from cool to warm. This demonstration simulates what happens when a dark asphalt road gets much hotter than the air around it--the air next to it becomes hotter than the higher air and light traveling through this temperature gradient is bent so much that it appears reflected. The shimmering water on a road's surface or the blue oasis in the desert are natural examples of blue skylight being...