Consider a neutron and an electron bound to each other due to gravitational force. Assuming Bohr’s quantization rule for angular momentum to be valid in this case, derive an expression for the energy of the neutron-electron system.

Applying Bohr’s quantization rule for angular momentum



And due to gravitational force balancing centripetal force.



Using both the equations we get



And


Now substituting these values in




Total energy = K.E + P.E



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