Английский язык. Ч.3 (Tests 10,11,12). Ильичева Н.А - 22 стр.

fundamental forces. One of these is the gravitational force. The other three are
the electromagnetic force, the weak force, and the strong force.
   Gravity is the most familiar of the forces, being responsible for keeping us in
orbit around the Sun as well as keeping our feet firmly planted on earth. The
mass of an object measures how much gravitational force it can exert as well as
feel. The electromagnetic force is the next most familiar of the four. It is the
force driving all of the conveniences of modern life – lights, computers, TVs,
telephones. It underlies the awesome might of lightning storms and the gentle
touch of a human hand.
   The strong and weak forces are less familiar because their strength rapidly
diminishes over all but subatomic distance scales; they are the nuclear forces.
This is why these two forces were discovered much more recently. The strong
force is responsible for keeping quarks “glued” together inside of protons and
neutrons and keeping protons and neutrons tightly crammed together inside
atomic nuclei. The weak force is best known as the force responsible for the
radioactive decay of substances such as uranium and cobalt.

                                     Text C

                    Quantum Mechanics – A New Theory
   The new theory, called quantum mechanics, unifies the wave – particle
duality into a single consistent theory. As a theory, quantum mechanics has been
extremely successful. It has successfully dealt with the spectra emitted by
complex atoms, even the fine details. It explains the relative brightness of
spectral lines and how atoms form molecules. It is also a much more general
theory that covers all quantum phenomena from blackbody radiation to atoms
and molecules. It has explained a wide range of natural phenomena and from its
predictions many new practical devices have become possible. Indeed, it has
been so successful that it is accepted today by nearly all physicists as the
fundamental theory underlying physical processes.
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