physics Term

ELECTROMAGTIC AND MAGNETIC
Achromatic:	capable of transmitting light without decomposing it into its constituent colors.
Alternating current:	The electric current that changes its direction periodically.
Ampere:	S.I. Unit of electric current, one ampere is the flow of one coulomb of charge per second.
Capacitance:	The ratio of charge stored per increase in potential difference.
Capacitor:	Electrical device used to store charge and energy in the electrical field.
Coherent source:	A source in which there is a constant phase difference between waves emitted from different parts of the source.
Coulomb's law:	The force between any two charges is directly proportional to the product of charges and inversely proportional to the square of the distance between the charges.
Direct current:	An electrical current which always flows in one direction.
Electric current:	The rate of flow of electric charge.
Electric field line:	An imaginary curve tangent to which at a point gives the direction of electric field at that point.
Electric potential energy:	The energy due to the position of a charge near other charges.
Electrical conductors:	The materials that have free electrons and allow current to flow through them.
Electrical insulators:	The materials which do not allow current to flow through them.
Electrical resistance:	The property to oppose the flow of current.
Electromagnetic induction:	The process in which current is induced in a coil whenever there is a change in the magnetic flux linked with the coil.
Electron volt:	The energy gained by an electron when it passes through a potential difference of one volt, it is equal to 1.60 x 10-19 Joules.
Farad:	The S.I.unit of capacitance, defined as the capacitance of a capacitor that, if charged to 1 C, has a potential difference of 1 V.
Faraday:	The electric charge required to liberate gram equivalent of a substance. 1 Faraday = 96485 coulomb/mole.
Fermat's principle:	An electromagnetic wave takes a path that involves the least time when propagating between two points.
Lenz's law:	The induced current always flows in such a direction that it opposes the cause producing it.
Magnetic domain:	Small regions in permanent magnets within which atomic or molecular magnetic moments are aligned parallel.
Magnetic field:	The region around a magnet where its magnetic force is experienced by other magnetic objects.
Magnetic reversal:	The changing of polarity of the earth's magnetic field as the north magnetic pole and the south magnetic pole exchange positions.
Magnetic wave:	The spread of magnetization from a small portion of a substance where an abrupt change in the magnetic field has taken place.
Ohm:	Unit of resistance; 1 ohm = 1volt/ampere.
Ohm's law:	The current flowing through a conductor is directly proportional to the potential difference across the ends of the conductor.
Open system:	A system across whose boundaries both matter and energy can pass.
Peltier effect:	The evolution or absorption of heat at the junction of two dissimilar metals carrying current.
Polarized Light:	Light whose constituent transverse waves are all vibrating in the same plane.
Power:	The rate of doing work.
Radiant energy:	The form of energy that can travel through space; for example, visible light and other parts of the electromagnetic spectrum.
Selenoid	A cylindrical coil of wire that becomes electromagnetic when a current flows through it
Semiconductors:	Elements whose electrical conductivity is intermediate between that of a conductor and an insulator.
Siemens:	The derived S.I. unit of electrical conductance, equal to the conductance of an element that has a resistance of 1 ohm, also written as ohm-1.
Superconductors:	Some materials in which, under certain conditions, the electrical resistance approaches zero.
Tesla:	The S.I. unit of magnetic flux density, defined as the magnetic flux density of a magnetic flux of 1 Wb through an area of 1m2.
Volt:	Unit of potential difference, equivalent to joule/coulomb.
Voltage drop:	The electric potential difference across a resistor or other part of a circuit that consumes power.
Watt:	S.I. unit for power; equivalent to joule/sec.