Light is transmitted by a bundle of optical fibers and/or a coiled length of plastic rod, regardless of the twists and turns in the path it must negotiate. Total internal reflection keeps the light confined.
How it works:
A HeNe laser is used as the source of light. The bundle of optical fibers consists of a very large (but unknown) number of individual glass fibers measuring 0.05 mm (0.002") in diameter. About 30 cm of the bundle is exposed at the end while the rest of the length is protected by a rubber sheath....
This block of uranium is of great historical significance -- it is a remnant of the WWII German Atomic Bomb Project. It was brought to Harvard by Prof. Edwin C. Kemble, Physics Dept. Chairman and also Deputy Science Director of the ALSOS mission in 1945. The American ALSOS mission was an intelligence effort to discover the extent of German progress toward atomic weapon development and its ultimate purpose was to secure all the uranium ore the Germans had confiscated during the war and finally close the books on the German program to build an atom...
Due to the oblateness of the Earth, the gravitational force between the Earth and the Sun sets up a couple which causes the Earth's axis of rotation to precess. An adapted globe shows what is meant by precession.
How it works:
An old 8" (19cm) globe has been modified 1 to allow it to precess on its axis. A 23° cone is cut into the south pole, and a cone of metal supported by a metal equatorial ring has been inserted. This makes the globe bottom heavy (and...
Archimedes' principle states that the buoyant force or upthrust is equal to the weight of fluid displaced. An object with equal mass but a lower density occupies more volume so displaces more water; it therefore experiences a greater upthrust.
How it works
This demo compares the buoyant force acting on two 1kg masses, one of aluminum and one of brass. Each in turn is lowered into a beaker of water using a spring balance (figure 1). The aluminum, having the lower density, experiences the greater upthrust and a reduction in weight from 10N to about...
Ball shot horizontally, one dropped vertically; both hit the ground at the same time.
What it shows:
The horizontal and vertical motions of a projectile are independent of each other. So two objects falling under the influence of gravity from the same height will reach the ground simultaneously, regardless of their horizontal velocities.
A physical pendulum with two adjustable knife edges for an accurate determination of "g".
What It Shows
An important application of the pendulum is the determination of the value of the acceleration due to gravity. By adding a second knife-edge pivot and two adjustable masses to the physical pendulum described in the Physical Pendulum demo, the value of g can be determined to 0.2% precision.
How It Works
Using a simple pendulum, the value of g can be determined by...
Selection of mounted tuning forks and rubber hammer.
How it works:
Each tuning fork is mounted on a wooden sound box to amplify the sound (they're very difficult to hear without the box). A microphone/preamp/scope setup may be used to visually demonstrate the pure sinusoidal sound wave. Additionally, a frequency analyzer shows a single frequency component (however, if the gain is turned up high, you may also see the frequency components due to the resonances of the sound box or harmonics of the tuning fork if it was whacked too hard). One of the...
The effect of length, tension, diameter, and kind of material on the pitch of a vibrating string is demonstrated. One may also show the harmonics of a vibrating string.
How it works:
The sonometer is a long hollow wooden box along the top of which are stretched one or more strings rigidly attached to the box at one end, with provision at the other for changing their tension. If there is just one string, it's known as a monochord. The monochord illustration is from John Tyndall's book entitled Sound, (...