NUCLEAR FUSION-RADIOACTIVITY
 
 
NUCLEAR FUSION
 
"The process of forming heavy nucleus from two or more light nuclei in
which energy is released is called "NUCLEAR FUSION."
OR
The combining of two lighter nuclei to form a relatively heavier
nucleus with the release of energy is called "NUCLEAR FUSION."
EXAMPLE
 
FUSION OF DEUTERIUM AND TRITIUM
 
When 1H2 and 1H3 nuclei are brought together they form 2He4 nucleus with the release of energy.
1H2+1H3 2He4+0n1+Energy.
CHARACTERISTICS OF FUSION
 
(1) Energy release during a fusion process in greater than that of fission.
(2) To produce a fusion process a very high temperature is required to over come repulsion between      positive nuclei.
DEFINE RADIOACTIVITY. WRITE PROPERTIES OF RADIOACTIVE RAYS.
RADIOACTIVITY
 
All the elements having atomic number greater than 82 emit invisible radiation all the time. The phenomenon of emission of these powerful rays is called "Natural Radioactivity" and the element that emits such rays is called "Radio Active Element".
TYPES OF RADIO ACTIVE RAYS
 
There are three types of radioactive rays:
a-Rays
b-Rays
g-Rays
PROPERTIES OF a-RAYS
 
(a) NATURE: a - rays consist of α particle. Each α particle consists of Helium(2He4) nucleus.
(b) CHARGE: a - particle carry positive charge.
(c) MASS: Mass of each a - particle is 4 times that of a proton or H-atom.
(d) IONIZATION: Ionization power of a - rays is very high.
(e) PENETRATION POWER: Penetration power of a - rays is very small.
(f) FLUORESCENCE: a - rays produce fluorescence in different substances.
(g) EFFECT ON HUMAN BODY: a - rays produce burn and sore on human body.
(h) ARTIFICIAL RADIO ACTIVITY: a - rays can produce artificial radioactivity is certain nuclei.
PROPERTIES OF b-RAYS
 
(a) NATURE: b - rays consist of fast moving electrons.
(b) CHARGE: b - rays have negative charge.
(c) VELOCITY: Velocity of b - rays is from 9 x 107 m/sec to 27 x 107 m/sec.
(d) EFFECT ON PHOTO GRAPHIC PLATE:b - rays affect photo graphic plate.
(e) IONIZATION POWER: Ionization power of b - rays is very small.
(f) KINETIC ENERGY: Kinetic energy of b - rays is less than that of a - rays.
(g) FLUORESCENCE: b - rays produce fluorescence in different substance.
PROPERTIES OF g-RAYS
 
(a) NATURE: g - rays are electromagnetic radiation.
(b) CHARGE: g - rays are no charge.
(c) VELOCITY: g - rays travel with the velocity of light that is 3 x 108 m/sec.
(d) PENETRATION POWER: Penetration power of g - rays is very large. It is about hundred times      larger than that of b -rays.
(e) FLUORESCENCE: g - rays produce feeble fluorescence When incident on screen coated with barium      platino cyanide.
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