Bohr S Model For Hydrogen Atom

An electron in hydrogen atom makes a transition where , and are principal quantum numbers of the two states. Assuming Bohr?? model to be valid, the time period of the electron in the initial state is eight times that in the final state. The possible

The ionization energy of is equal to

The ionisation energy of an electron in the ground state of helium atom is . The energy required to remove both the electron is