Read Bohr Orbits: Scale Radius, Speed and Field
For a hydrogenic ion, the electrostatic force sets the orbit while angular-momentum quantisation selects the allowed radius. Compare the same quantum number before scaling with nuclear charge.
Bohr-Orbit Scaling for Hydrogenic Ions is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Start with the condition
Use r-n proportional to n²/Z, speed proportional to Z/n, and orbital magnetic-field scaling only after finding the new radius and frequency.
Build the governing relation
Keep the ion charge Z and orbit index n separate.
Finish with a physical check
Check the limiting case before selecting an option: remove the special feature in the diagram or make the relevant parameter very large or very small. The result should reduce to a familiar relation.
OlympIQ exam lens
- ✓State the physical condition before choosing a formula.
- ✓Keep direction, sign and constraint information explicit.
- ✓Test one limiting case before committing to an option.
Applying hydrogen ground-state ratios directly without the Z and n factors misses the competing changes in radius and speed.
Ready to try the pattern?
100% coverage across the linked question.
Practise the linked question