Answer
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Work Step by Step
Bohr predicted the physical significance of any state in hydrogen atom By observing the following expression, for energy levels available to the electron in the hydrogen atom.
$E=-2.178\times10^-$$^1$$^8J(Z^2/n^2)$
Here 'n' is an integer and "z" is the nuclear charge. Bohr was able to calculate hydrogen atom energy levels that exactly matched the values obtained by experiment.
The negative sign in the above equation simply means that the energy of the electron bound to the nucleus is lower than it would be if the electron were at an infinite distance $n=\infty$ from the nucleus . Where there is no interaction and the energy is zero.
$E=-2.178\times10^-$$^1$$^8J(Z^2/n^2)=0$
The energy of the electron in any orbit is negative relative to this reference state.
