MEDICAL ENTRANCE TIPS

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  Atomic structure
  1. Electrical nature of matter was proposed by Michael Farady.
  2. Cathode rays were discovered by Plucker.
  3. When cathode rays are allowed to strike a screen coated with ZnS a fluorescent spot will be formed.
  4. Electrons were discovered by J.J. Thomson
  5. The name electron was given by Stoney
  6. Charge of electron = 1.6 x 10-19 C or 4.8 x 10-10 esu.
  7. Mass of electron - 9.1 x 10-31 Kg or 0.000549 amu or 1/1837 of the hydrogen atom.
  8. e/m ratio (specific charge) was determined by J.J. Thomson
  e/m = E/rH2 E - Strength of electric field
  H - Stregth of magnetic field
  r - radius of the circular path
  e/m ratio = 1.76 X 108 c/g or 5.28 X 1017 esu/g
  9. Charge of the electron was determined by Millikan’s Oil Drop experiment.
  10. Mass of an electron varies with its speed.
  11. Electrons are universal constituents of all matter.
  12. Proton were discovered by Goldstein.
  13. The name Proton was given to canal rays by Rutherford.
  14. Mass of Proton - 1.672 x 10-27 Kg or 1.0072 amu.
  15. Specific charge of a proton - 9.57 x 107 C/kg.
  16. e/m ratio of the particles of the canal rays was highest when hydrogen was used as the discharge gas. The ratio depends on the nature of the gas.
  17. Neutrons were discovered by Chadwick.
  18. Mass of neutron - 1.675 x 10-27 Kg or 1.0086 amu.
  19. The mass of a neutron is slightly greater than that of a proton.
  20. Nucleus was discovered by Rutherford by the scattering of a - particles on gold foil.
  (Gieger-Marsden expt)
  21. Most of the a - particles passed through the foil without deflection- Atom consists of mostly
  empty space.
  22. Radius of the nuecleus - 10-13 cm
  23. Radius of an atom - 10-8 cm