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State and explain Bohr's postulates forhydrogen atom. |
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Answer» Solution : Bohr gave following three postulates for hydrogen atom: 1. An electronrevolves round the NUCLEUS in certain specified circular ORBITS in which it does not radiate ENERGY. The centripetal force required for uniform circular motion in such a stationary orbit is provided by electrostatic force of attraction. Thus, `(m v_(n)^(2))/(r_(n)) = (1)/(4pi in_(0)) .(e^(2))/(r_(n)^(2))""......(i)` 2.Foran orbit to bestationary(ornon - radiating ) , theangularmomentum of theelectronmust bean integer multipleof `(h)/(2pi)`where h is thePlanck .s contant . Thus `L_(n) = m v_(n) r_(n) = (nh)/(2pi)"".......(ii)` 3. Wheneveran electron shift from oneof itsspecified non - radiatingorbitto anothersuchorbit , itemits /absorbs a photon whoseenergyis equalto theenergydifferencebetweenthe initial and final states . Thus . `E_(i)= E_(f)= HV = (hc)/(LAMBDA)""............(iii)` |
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