Posts

Image
 VAN DER FORCES Attractive forces between uncharged molecules are known as van der Waals forces These forces may be divided into three groups. Dispersion or London forces. These are due to transient Polarization.  Dipole Dipole attraction . These are due to permanent polarization Hydrogen Bonding        LONDON FORCES The negative electrons in a neutral molecules are balanced by positive charges on the nucleus. Since he electrons are in motion the centre of density of electrons does not coinside continously with centre of density  of positively charged nuclei, the molecules acquire an electric dipole. Polarized  molecules exert an attraction for other molecules having dipole. Consider the case of Helium. The greater the polarizability of a molecule, the stronger are London forces The polarizability increases with number of electrons and their distance from nuclus These forces are very short range  The inert gases have weak VAN DER WAALS force...
Read more

PARTICLE NATURE OF ELECTROMAGNETIC RADIATION: PHOTO ELECTRIC EFFECT

Particle Nature of Electromagnetic Radiation:  Planck’s Quantum Theory The important postulates of quantum theory proposed by Max Planck are: 1. Atoms and molecules could emit or absorb energy not in a continuous manner, but discontinuously  in small packets of energy called quanta or photons.  2. The energy (E ) of each quantum of radiation is proportional to its frequency (ν). It is expressed by the equation, E = hν Where ‘h’ is known as Planck’s constant and its value is 6.626×10–34 J s. Photoelectric effect It is the phenomenon of ejection of electrons by certain metals (like potassium, rubidium, caesium  etc.) when light of suitable frequency incident on them. The electrons ejected are called photoelectrons.  This phenomenon was first observed by H Hertz. The important characteristics of photoelectric effect are: 1. The electrons are ejected from the metal surface as soon as the beam of light strikes the surface. i.e.,  there is no time lag between the...
Read more

2.2.2 RUTHERFORD'S NUCLEAR MODEL OF ATOM

Image
Rutherford’s Nuclear Model of Atom Rutherford proposed an atom model based on his α–particle scattering experiment. He bombarded a very  thin gold foil with α–particles. The Experiment: A stream of high energy α–particles from a radioactive source was directed at a thin gold  foil. The thin gold foil was surrounded by a circular fluorescent zinc sulphide screen. Whenever α–particles  struck the screen, a tiny flash of light was produced at that point. Observations: The important observations made by Rutherford are: 1. Most of the α– particles passed through the gold foil without any deviation. 2. A small fraction of the α–particles was deflected by small angles. 3. A very few α– particles (∼1 in 20,000) bounced back, that is, were deflected by nearly 180°. Observations: The important observations made by Rutherford are: 1. Most of the α– particles passed through the gold foil without any deviation. 2. A small fraction of the α–particles was deflected by sm...
Read more

3.INTEGRATION USING TRIGNOMETRIC IDENTITIES

Image
Read more

5. INTEGRATION BY PARTIAL FRACTIONS

Image
Read more

8.2 TEXTBOOK EXERCISE

Image
Read more

INTEGRALS FORMULA BOX

Image
TEXTBOOK EXERCISE 7.1 TEXTBOOK EXERCISE 7.2 TEXTBOOK EXERCISE 7.3 TEXTBOOK EXERCISE 7.4 TEXTBOOK EXERCISE 7.5 Formula BOX TRIGNOMETRY DIFFERENTIATION 
Read more