Physics Glossary – S

Schimidt Telescope

Light passes through a thin correcting plate, is reflected by a large short-focus spherical mirror, and focused on a curved photographic plate. In this kind of telescope, corrects aberration, croma and astigmatism. Named after Bernhard Schmidt.

Schrodinger’s Cat

Is a thought experiment that attempts to illustrate the incompleteness of the theory of quantum mechanics when going from subatomic to macroscopic systems. A cat is placed in a sealed box. Attached to the box is an apparatus containing a radioactive nucleus and a canister of poison gas. When the nucleus decays, it emits a particle that triggers the apparatus, which opens the canister and kills the cat. If the box is not open then that cat could be alive or dead, we don’t know. But if we open the box then we will know the state of the cat.

Seebeck Effect (Peltier Effect)

A when an current is passed through two dissimilar conductors (n-type and p-type) that are connected to each other at two junctions (Peltier junctions). The current drives a transfer of heat from one junction to the other. Or Vice Versa a temperature difference causes a current to flow between them.

Semiconductors

Are materials with electrical conductivities that are intermediate between those of conductors and insulators. Semiconductors are useful for electronic purposes because they can carry an electric current by electron propagation or hole propagation, and because this current is generally uni-directional and the amount of current may be influenced by an external agent (see diode, transistor, amplifier etc.).

Simple Harmonic Motion

Is the motion of a particle about a fixed point such thats its acceleration is proportional to its displacement from the fixed point. The acceleration is directed toward the point. An example of this in terms of a mass on a spring or a pendulum.

Solar Wind

A stream of particles (mostly high-energy protons ~ 500 Kev) that is continually ejected from the surface of the Sun. The composition of this plasma is identical to the Sun’s corona, 73% hydrogen and 25% helium with the remainder as trace impurities, and is ionized. Near Earth, the velocity of the solar wind varies from 200km/s-889km/s. The average is 450 km/s. Approximately 3000 tons of material is lost from the Sun every hour as solar wind.

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