An electron in a hydrogen atom undergoes a transition from an orbit...

An electron in a hydrogen atom undergoes a transition from an orbit with quantum number \( n_{i} \) to another with quantum number \( n_{f} . V_{i} \) and \( V_{f} \) are respectively the initial and final potential energies of the electron. If \( \frac{V_{i}}{V_{f}}=6.25 \), then the smallest possible \( n_{f} \) is