What it shows:

A beam of light is distorted due to turbulent convection currents in air. This is a model of atmospheric distortion that affects seeing conditions in ground based optical and infrared astronomy.

How it works:

Turbulent air is provided by an electric stove ring, that heats the air above it as the warm earth dues to air sitting above it. The turbulent currents set up alter the refractive index of the air in a disordered and rapidly changing way. Light from a point source passing through these conditions is blurred...

What it shows:

A beam of white light incident on a giant raindrop (simulated by a water-filled round flask) produces a full rainbow of colors. As with real rainbows, one can also see that the light intensity inside the rainbow is much greater than outside the rainbow.

How it works:

A Florence (round-bottomed) flask is completely filled with water and sealed with a rubber stopper. A Beseler slide projector ¹ serves as the sunlight. The light incident on the giant raindrop is refracted, reflected, and refracted once more, back in the direction of the...

What it shows:
A mechanical analogy of a wave front consisting of two wheels linked by an axle. It simulates refraction by rolling across a boundary between two surfaces having different rolling friction and thus...

A lens immersed in a fish tank of water seems to lose its refractive powers to focus light.

What it shows:

A lens seems to lose its ability to focus when immersed in water. This models the inability of us...

What it shows:

Hero's Principle states that light undergoing a reflection from a plane surface will follow the path of least distance. Here is a mechanical analog showing that when the angle of incidence equals the angle of reflection, the path length is minimized.

How it works:

The light path is represented by a 2m length of nylon rope that runs from a fixed end, 'reflects' around a pulley, back up to a second pulley (figure 1). The surplus rope is held taught by a 1kg mass. The pulleys, 6cm in diameter are free to move...

What it shows:

The simplest method of controlling light to form an image is to use an opaque mask with a pinhole in it. Rectilinear propagation of light explains all (nearly). A video camera is substituted for the old prototypal shoe box so that an entire audience can see the pinhole image "live."

How it works:

An extremely light-sensitive video camera ¹ sans lens substitutes for the pinhole camera box and film. The front of the Newvicon is the image plane and, as this sits right behind the faceplate of the camera...

What it shows:

All colors can be created from a combination of the three primary colors of red, green and blue. The secondary colors of cyan, magenta and yellow are created from a combination of two primaries, and white light is perceived from the combination of all three.

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What it shows:

Like visible light, invisible infra-red radiation can be refracted by lenses to produce an image on a screen. Indeed, a slide projector designed for visible light is used as the imaging device; a heat- sensitive screen makes the invisible IR image visible.

How it works:

Our IR source is a 1000 watt "lantern slide" projector ¹ from which we have removed the special heat-absorbing glass in the condenser assembly. The slide to be imaged is some kind of lettering, like the name of the course (Science A-29...

Detection of IR radiation from hair dryer and/or special IR source.

What it Shows:

Detection of infra-red radiation by the rotation of a paddle-wheel vane inside a low pressure flask.

How it Works:

A radiometer consists of a partially evacuated flask containing a four bladed vane (see figure 1). One side of each blade is a matt black, the other silver. The black surface, being a better absorber and radiator of heat, warms the air above its surface more than the silver. The resulting higher kinetic energy of these air...

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What it shows:

White light is shown, á la Newton's demonstration of dispersion by a prism, to be composed of a continuous spectrum of colors.

How it works:

A large brilliant spectrum is produced by using a 1 kW carbon arc light source ¹ with adjustable slit, a "fast" f/0.9 imaging lens, ² and a highly dispersive in-line prism. ³ The spectrum easily fills a two meter wide screen with vibrant colors. An alternative (more compact) setup consists of a Beseler slide projector ⁴ which...

What It Shows

The amplitudes and relative phases of the voltages across the individual elements of a series RLC circuit varies with the frequency of the driving voltage. The voltages of the three elements plus the driver...

What it shows:

The transmission and detection of radio frequency electromagnetic radiation by use of LC oscillator circuits recreates the discovery by Hertz of a method to generate and detect electromagnetic waves.

How it works:

The core of the apparatus (figure 1) is a series LRC circuit (the R provided by the circuit resistance). The inductor L is a 1m diameter loop made of 1 inch copper tubing which also serves as the radiating antenna. A transformer ¹ supplies 15kV to charge up the capacitor ² until...

Light, passing through heavy glass, has its direction of polarization rotated slightly if a magnetic field is applied to the glass.

What it shows:

A thin wafer of Ferromagnetic Garnet reveals its magnetic domain alignment as light and dark serpentine patterns when viewed between crossed Polarizers. These domains can be flipped by an external magnetic field, changing the pattern structure.

How it works:

The magnetic bubble apparatus consists ¹ of a thin (8-12μm) single crystal film of Ferromagnetic Garnet (FMG) sandwiched between a pair of crossed Polaroids. The FMG crystals are magnetically anisotropic, that is, they have a strong tendency to orient...