Ncert Exercises & Solutions

The gravitational force between H-atom and another particle of mass m will be given by Newton's law \(F=\frac{GMm}{r^2},\) where r is
in km and

1.	M=m_proton+m_electron.
2.	M=m_proton+m_electron-\(\frac{B}{c^2}\) ( B=13.6 eV ).
3.	M is not related to the mass of the hydrogen atom.
4.	M=m_proton+m_electron-\(\frac{\|V\|}{c^2}\) ( \|V\| = magnitude of the potential energy of electron in the H-atom).

(2) Hint : There is reduction in the mass as some mass is lost in the form of energy .

Step 1 : Find the value of M .

Given,

F = \frac{GMm}{r^{2}}

M = effective mass of hydrogen atom

= mass of electron + mass of proton - \frac{B^{2}}{C}

where B is BE of hydrogen atom = 13.6 eV