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An atom consists of a nucleus and electrons which revolve around it.Nucleus
consists of PROTONS and NEUTRONS (together called Nucleons ) which are
bound together by the STRONG FORCE . Our common sense leads us to think
that if this is the case ,the mass of an atomic nucleus =mass of (protons+neutrons).
But in fact this is not the case.The experiments shows that mass of an atomic

nucleus is always less than the combined mass of its nucleons. This difference
which always occurs is called the MASS DEFECT .This mass defect when
converted to energy by Einstein's famous mass-energy equation E=MC^2 is
called the BINDING ENERGY (BE).This energy can be thought of as the energy
that is spent for the formation of the atomic nucleus . Thus this much Energy must
be provided to an atomic nucleus to split it up into Protons and Neutrons . Binding
Energy is same for all atoms of a particular element (eg .Helium ). Thus,more the
Binding Energy for a particular atom (eg .Oxygen atom) more energy is needed to
split it up or it is MORE STABLE . Thus if a less stable stable element(s) is
somehow CONVERTED to a more stable element(s),the resultant element(s) will
have a much higher Binding Energy or HIGHER THE MASS DEFECT FOR THE
RESULTANT ATOM .THIS DIFFERENCE IN THE BE IS THE ENERGY WE
COULD USE FOR POWER GENERATION OR FOR ATOM BOMBS .

FISSION & FUSION are the two ways to thus convert less stable atoms to more
stable ones . In FISSION,a less stable LARGE nucleus SPLIT into more stable
SMALL nuclei (or atoms).In FUSION ,unstable SMALL nuclei FUSE together to
form a more stable LARGE nucleus(or atom).Here too,as said ENERGY equal to
BE of(resultant nucleus )-BE(fusing nuclei ) is released .This energy released is
MORE THAN WE GET FROM FISSION OF THE SAME MASS & MUCH MUCH
MORE FROM COAL of similar mass.FUSION is the energy source of stars like
SUN.In sun the most prominent REACTION is the PROTON-PROTON CYCLE(P-P)
where protons (protn is Hydrogen nucleus) fuse together to form Helium in a series
of steps. But, as we can see ,for example protons have same charge and there is
REPULSION between two PROTONS and thus energy is needed to overcome this
REPULSION ENERGY BARRIER to make Fusion happen . This is possible only at
very HIGH TEMPERATURES(~10^9)and hence called THERMONUCLEAR
REACTIONS.Such a HIGH temperature is very difficult to be produced in Earth by
man .This is the main PRACTICAL PROBLEM which prevents us from using fusion
for our Energy needs . But RESEARCHES are on the way to find a way to produce
and maintain such temperatures.The MOST FEASIBLE FUSION FOR MAN'S
ENERGY NEEDS APPEARS THAT BETWEEN DEUTRONS AND ALSO
BETWEEN DEUTIRIUM AND TRITIUM.Techniques like MAGNETIC AND INERTIAL
CONFINEMENT methods are required since no SOLID CONTAINER can
withstand such high TEMPERATURES .The first thermonuclear reaction on earth
occured at Eniwetok Atoll on Nov 1,1952 when USA exploded a fusion device.
FUSION is undoubtedly bound to become the FUEL OF THE FUTURE .

Learn more about this author, Sree Hari.
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