Question 12: NCERT Solutions for 12th Class Physics: Chapter 12-Atoms
The gravitational attraction between electron and proton in a hydrogen atom is weaker than the coulomb attraction by a factor of about 10-40. An alternative way of looking at this fact is to estimate the radius of the first Bohr orbit of a hydrogen atom if the electron and proton were bound by gravitational attraction. You will find the answer interesting.
The radius of the first orbit in Bohr’s model is calculated by considering the electrostatic force between electrons and proton in nucleus.
This radius is much greater than the estimated size of the whole universe.
Check the complete chapter with solutions.
NCERT Solutions for 12th Class Physics: Chapter 12-Atoms