

Cathode Rays
Cathode rays, discovered by Sir William Crooke
and its properties are
- travel in straight lines.
- Produce fluorescence.
- can penetrate through thin foils of metal and deflected
by both electric and magnetic fields. - have velocity ranging 1/30th to 1/10th of the
velocity of light.
Positive or Canal Rays
- These rays were discovered by Goldstein.
- The positive ray consists of positively charged
particles. - These rays travel in straight line.
- These rays are deflected by electric and magnetic
fields. - These rays can produce ionization in gases.
X-Rays - X-rays are electromagnetic waves with wavelength
range 0.1 A-100 A. - X-rays were discovered by Roentgen.
- X-rays travels in straight line.
- Long exposures of X – rays in injurious for human
body. - X – rays shows photoelectric effect.
Uses of X-Rays - In medical sciences X-rays are used in surgery for
the detection of fracture, diseased organs, foreign
matter like bullet, stones etc. They are used in
treatment of cancer and in skin diseases. - In Engineering, X-rays are used in detecting faults,
cracks, flaws and gas pockets in the finished metal
products and in heavy metal sheets. - In Scientific Work, X-rays are used in studying
crystal structure and complex molecules. - In Custom Department X-rays are used in custom
department for detection of banned materials kept
hidden.
Radioactivity - Radioactivity was discovered by Henry Becquerel,
Madame Curie and Pierre Curie for which they
jointly won Nobel Prize.
Nuclear Fission - Atom Bomb is based on nuclear fission. U235 and Pu239
are used as fissionable material. - Nuclear fission was first demonstrated by Halin and
Fritz Strassmann.
Nuclear Fusion - When two or more light nuclei combined together to
form a heavier nucleus is called as nuclear fusion. - For the nuclear fusion, a temperature of the order of
108 K is required. - Hydrogen Bomb was made by the American
Scientist in 1952. This is based on nuclear fusion.
It is 1000 times more powerful than atom bomb.