Read Charged Pendulums: Resolve Force Before Geometry
The angle of each charged bob comes from its own force balance. Equal string lengths do not imply equal angles when mass or charge differs.
Electricity questions depend on identifying charge, a conducting path and the condition that controls current or magnetic effect.
Start with the condition
Draw Coulomb force horizontally, weight vertically and tension along the string.
Build the governing relation
Both bobs feel equal and opposite Coulomb forces, so compare q1 q2/(m1 g) with q1 q2/(m² g) rather than cancelling unequal masses too early.
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.
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- ✓State the physical condition before choosing a formula.
- ✓Keep direction, sign and constraint information explicit.
- ✓Test one limiting case before committing to an option.
Treating the two tensions or two angles as automatically equal loses the key asymmetry in the setup.
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