Chemistry · Structure Of Atom · NEET
When you place an atom inside a strong MAGNETIC field and look at its spectrum, each single spectral line splits into two or more closely spaced lines. This splitting is called the Zeeman effect. The magnetic field affects the energy of the electron slightly differently for different orientations, so one line becomes several. Remember: Zeeman = magnetic field.
The Stark effect is also a splitting of spectral lines, but it happens when the atom is placed in an ELECTRIC field, not a magnetic field. So the only difference is the type of field: Zeeman uses a magnetic field, Stark uses an electric field. Both give the same visible result (lines split), just from different causes.
Bohr's model gives only ONE fixed energy for each orbit (energy depends only on n). It has no way to account for extra energy differences created by an outside magnetic or electric field. So Bohr predicts one line where experiments actually show several. Because it cannot explain this splitting, the Zeeman and Stark effects are counted as limitations of Bohr's model. This is a favourite NEET point.
Zeeman effect = MAGNETIC field. Stark effect = ELECTRIC field. NEET loves to swap these two in options to trip you up. A quick trick: both 'Zeeman' and 'magnet' can be linked in your mind, so the other one, Stark, must be electric.
No. For NEET you only need to know the definitions (which field causes which splitting) and that both are LIMITATIONS of Bohr's model. You do NOT need any formula or derivation. Just memorise: Zeeman-magnetic, Stark-electric, and both show Bohr was incomplete.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Magnetic. The Zeeman effect is the splitting of spectral lines when an atom is placed in a magnetic field.
Electric. The Stark effect is the splitting of spectral lines in an electric field.
Yes. Bohr's model cannot explain the splitting of spectral lines in either a magnetic field (Zeeman) or an electric field (Stark), so both are listed as its limitations in NCERT.
Zeeman = magnetic field, Stark = electric field. Since NEET options often swap them, memorise this pair firmly.
