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Physics Definitions Start from S

Solar Atmosphere - The atmosphere of the Sun. An atmosphere is generally the outermost gaseous layers of a planet, natural satellite, or star. Only bodies with a strong gravitational pull can retain an atmosphere. Atmosphere is used to describe the outer layer of the Sun because it is relatively transparent at visible wavelengths. Parts of the solar atmosphere include the photosphere, chromospheres, and the corona.

Solar Limb - The apparent edge of the Sun as it is seen in the sky.

South Atlantic Anomaly - The region over the South Atlantic Ocean where the lower Van Allen belt of energetic, electrically charged particles is particularly close to the Earth's surface. The excess energy in the particles presents a problem for satellites in orbit around the Earth.

Spectral Line - A line in a spectrum due to the emission or absorption of electromagnetic radiation at a discrete wavelength. Spectral lines result from discrete changes in the energy of an atom or molecule. Different atoms or molecules can be identified by the unique sequence of spectral lines associated with them.

Spectrograph - An instrument that spreads light or other electromagnetic radiation into its component wavelengths (spectrum), recording the results photographically or electronically.

Spectrometer - An instrument for measuring the intensity of radiation as a function of wavelength. See Spectrograph.

Spectrum - Electromagnetic radiation arranged in order of wavelength. A rainbow is a natural spectrum of visible light from the Sun. Spectra are often punctuated with emission or absorption lines, which can be examined to reveal the composition and motion of the radiating source.

Speed of light - 186,000 miles per second (or 300,000,000 meters per second). The universal "speed limit" that is the fastest that anything can go.

Spin - The characteristic of a particle that causes it to rotate about an axis in a consistent direction.

Strong Force - A fundamental particle. There are six quarks (but only five have been observed) plus their antiquarks. Each quark and antiquark exists in three "colors."

Subatomic particle - Any particle smaller than an atom.

Sunspot - A temporary disturbed area in the solar photosphere that appears dark because it is cooler than the surrounding areas. Sunspots consist of concentrations of strong magnetic flux. They usually occur in pairs or groups of opposite polarity that move in unison across the face of the Sun as it rotates.

Superconductor - Force that binds quarks and holds the nucleus of an atom together. It is the strongest force in nature.

Surface Plot - A three-dimensional plot mapping the intensity of radiation from a region as a distorted surface. More intense radiation is represented by higher points on the surface. Therefore, regions of intense radiation resemble mountains on the earth.

Scalar - Quantity, like distance, that has only a magnitude, or size.

Schematic Diagram - Representation of electric circuit using symbols.

Scientific Notation - Numbers expressed in form M * 10 ^ n , where 1< M < 10, and n is an integer.

Scintillation - Flash of light emitted when substance is struck by radiation.

Second - SI unit of time.

Second Law of Thermodynamics - Heat flow only from region of high temperature o region of lower temperature.

Secondary Coil - Transformer coil in which varying EMF is induced.

Secondary Light Colors - Yellow, Cyan or Magenta Light.

Secondary Pigment - Red, Green, or Blue Pigment.

Self-Inductance - Induced EMF produced in coil by changing current.

Semiconductor - Material in which electrical conduction is smaller than that in a conductor, but more than in insulator.

Series Circuit - Circuit in which electrical current flows through each component, one after another.

Series Connection - Arrangement of electrical devices so that there is only one path through which current can flow.

Short Circuit - Low resistance connection between two points, often accidental.

SI - Internationally agreed -upon method of using the metric system of measurement.

Significant Digit - Reliable digits reported in a measurement.

Simple Harmonic Notion - Motion caused by linear restoring that has a period independent of amplitude of motion.

Simple Machine - Machine consisting of only one lever, inclined plane, wedge, screw, pulley, or wheel and axle.

Sine - The ratio of the opposite side and the hypotenuse.

Sliding Friction - Force between two surfaces in relative motion.

Slope - Ratio of the vertical separation, or rise to the horizontal separation, or run.

Solid - State of matter with fixed volume and shape.

Sound Level - Quantity measuring logarithm of sound intensity in decibels.

Spark Chamber - Device used to detect path of charged subatomic particles by a spark that jumps along path of ionization created in a gas.

Specific Heat - Thermal energy needs to change temperature of unit mass of substance one Kelvin.

Spectroscope - Device used to study spectrum of material.

Spectrum - Collection of wavelengths in electromagnetic spectrum.

Speed - Ratio of distance traveled to time interval.

Speed of Light - In vacuum, 2.9979458 * 10^8 m/s.

Spherical Aberration - Inability of spherical mirror to focus all parallel rays to a single point.

Standing Wave - Wave with stationary nodes.

Static Friction - Force that opposes start of motion between two surfaces.

Step-Down Transformer - Transformer with output voltage smaller than input voltage.

Step-Up Transformer - Transformer with output voltage larger than input voltage.

Stimulated Emission - Emission of photon from excited atom caused by impact of photon of same energy.

Strong Nuclear Force - Force of very short range that holds neutrons and protons in nucleus together.

Superconductor - Electrical conductor that has no resistance and low temperatures.

Surface Wave - Wave on surface of liquid with characteristics of both longitudinal and transverse waves.

Symmetry - Property that is now charged when operation or reference frame is charged.

Synchrotron - Device to accelerate particles in which particles move in circular path.

System - Defined collection of objects.

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