Physics Notes
1. Amplitude Modulation Notes :-https://engineerstutor.com/2018/10/03/am-amplitude-modulation-mathematical-derivation/
I. The Rutherford Model OF The Atom
The first exploration of the structure of the atom was made by Rutherford in 1911 making use of α-particles. He bombarded a thin gold foil with α-particles (helium nuclei, which are positively charged particles with an atomic mass number of 4) and found that very many α-particles passed through the gold foil without being deflected, but some of them were deflected through a large angle. The inference was that much of the atom has void space between them, allowing most of the α-particles to pass straight through, but with some particles being deflected owing to their passing close to, or colliding with, a central mass (nucleus) or very small dimensions. The effective diameter of the gold atom is 0.3 nm and the diameter of the nucleus is about 1/10,000 of this size. The first postulation about electrons was that they are in orbit around the central nucleus just as planets round the sun. To incorporate these findings and the discovery of the electron, Rutherford proposed the following model of the atom: This model postulates a tiny, massive and positively charged nucleus around which the negative electrons orbit. In Fig. 2.1, an electron is revolving in a circular orbit of radius, r, with a constant velocity, v. The system is now subjected to two forces. Acting inwards will be electrostatic attraction given by Coulomb’s law
Here ε0 is the permittivity of free space. The other one is the centrifugal force, fc acting outwards. The value of this force is
where m is the mass of the electron and (v2/r) is its radial acceleration. The condition for orbit stability is fc = fe.
Thus,
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