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Glossary L

Lamb Shift
There is a difference between the first two energy levels
in the spectrum of hydrogen, this is called the Lamb Shift
after the Willis Eugene Lamb. [more]
Law of conservation of Energy/Momentum
Energy/momentum cannot be created or destroyed; it may
be changed from one form to another.
Law of Universal Gravitation
Gravitational force between two objects depends directly in the
product of their masses and inversely on the square of
their separation.
Laser
An optical device that produces very narrow beam
of monochromatic (one wavelength), coherence (in the same
phase) and intense light. It works by pumping electrons to a
higher excited state, the electron fall back and give out very
defined form of light. A laser was originally an acronym for
Light Amplification by Stimulated Emission of Radiation”.
[Physics 2000]
Name Charge Mass (GeV)
Electron -1 0.000511
Electron Neutrino 0 ~0
Muon -1 0.1056
Muon Neutrino 0 ~0
Tau -1 1.777
Tau Neutrino 0 ~0

Lepton

A lepton (Greek for “light”, as opposed
to hadrons which are “heavy”) is a subatomic particle that is
not made of quarks. They include the electron, the muon, the tau, and their respective neutrinos.
Light Year
The distance light can travel in one
year, roughly 10 million million kilometers. For example, the
nearest known star, Proxima Centauri is 4.22 light years away.
Light Emitting Diode
Is a semiconductor device that emits
incoherent monochromatic light when electrically biased in the
forward direction. This effect is a form of electroluminescence.
The color depends on the semiconducting material used, and can
be near-ultraviolet, visible or infrared. Nick Holonyak Jr. developed
the first practical visible-spectrum LED in 1962.
Latent Heat
Is the heat that is added to a system that changes the
physical state of the substance e.g. changing from a light
to a gas. [more]
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