Presentations

Single Photon Interference

Wave/particle duality observed in Young's double slit experiment with camera sensitive to individual photons.

What it shows:
In this demonstration we perform the double-slit interference experiment with extremely dim light and show that even when the light intensity is reduced down to several photons/sec, the audience can see the familiar Young's double-slit interference pattern build up over a period of time. This addresses the question of how can single photons interfere with photons that have already gone through the apparatus in the past, or with those that...

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Black Body Radiation Oven

What it shows:

Black body radiators in thermal equilibrium should emit the same spectrum of radiation, so inside a kiln at high temperature objects should appear the same color whatever their material.

How it works:

Place a piece of brick and an iron ball into a kiln (ours is a Blue M Electric Co. kiln with 25cm × 12cm × 10cm oven) that has a temperature range up to around 1000°C. Close the door and crank up the temperature to maximum. Depending on the type of kiln, it will take around 20 minutes to reach equilibrium (a good length...

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Periodic Potential

What it shows:

Ball bearings simulate atoms in a lattice sitting at local potential minimums. Giving them energy excites the atoms and they oscillate about their equilibrium positions in these wells; only with large amounts of energy can they be truly dislocated.

How it works:

A piece of wood 100 × 25 × 2cm acts as the ‘potential’ structure of the lattice. The atoms, 3cm diameter ball bearings sit at the bottom of a cosine varying potential cut to about 10cm depth in the wood by a jig saw.The balls are held in the 2-dimensional...

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Solid, Liquid, Gaseous CO2

Observation of phase changes with corresponding pressure changes.

A two ml. plastic microcentrifuge vial and a small shop vise are used together to melt dry ice.

Wear safety glasses for this demo. The vial can explode, or shoot out of the vice, from the pressure of liquid carbon dioxide. Set up a camera with a close shot of an empty vial before putting in a loaded vial.

Crush a pellet of dry ice to make pieces that fit into the vial. Place a couple of pieces in the vial, and snap the lid closed.

Immediately place the vial horizontally in the jaws of the vice,...

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Jumping Ring

Shoot the ring through the roof after dipping it in liquid N2; Lenz's law induced EMF in metal ring.

What it shows: 

The induced current in a metal ring is dramatically increased by lowering the ring's temperature.

How it works: 

Here is an extension of the ...

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Armillary Sphere

Model to show celestial sphere; larger version has capacity to show lunar motions.

What it shows:

The position and motions of heavenly bodies are projected against a hypothetical sphere of infinite radius, centered on the Earth, called the Celestial Sphere. With this demo you can explain the motions of the stars and of the Sun, and show various aspects of the seasons.

How it works:

The main features of the sphere itself are shown schematically in figure 1. The spherical wire cage defines the celestial sphere, its...

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Samples of Elements

First day of Gen Chem: Metals and non-metals; solids, liquid and gas elements; compound of elements.

Copper, sulfur, lead, iron, antimony, iodine, carbon as powder and graphite sample, mercury, copper iodate, oxygen balloon.

Iron Tin Reaction Kinetics

Dark red iron[III] solution is rapidly reduced to colorless iron[II] by addition of tin[II] chloride solution, with the rate depending on concentration and temperature.

Four medium footed cylinders are prepared with 100 ml of ferric chloride solution 0.01M with potassium thiocyanate solution added to make the dark red complex. One of the solutions should be hot, so just the iron and thiocyanate solutions in that cylinder, with a 150ml beaker for the demonstrator to fill with hot water from the water cooler, right before the demonstration.

The cylinders are on the bench top in...

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Buoyant Force Measurement

What it shows

We have three 20 oz. soda bottles, one filled with water, one filled with sand, and one filled with air. A spring scale shows the water-filled bottle to weigh approximately 6N in air, and nearly 0N when it is fully submerged in a large container of water. Since gravity is still acting on the bottle when it is submerged in the water, there must be a force of 6N pushing up on it. This is the buoyant force.

We can do the same experiment with the bottle of sand. This bottle weighs roughly 13N in air, but when it is fully submerged in water it weighs 6N less. Even...

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