Practice portal › Electric Charge and Properties › Electric Charge and Coulomb's Law
Asked in GSEB Board July 2017 · Equilibrium and small oscillations
Given: thread length L=2 m; like charges q on both spheres; no gravity.
Idea: with no weight, the only forces on each sphere are the Coulomb repulsion from the other sphere and the tension in its thread.
The repulsion acts along the line joining the spheres. Equilibrium needs the tension to be exactly opposite to it, which happens only when the thread lies along that same line.
At any smaller angle the repulsion has a part across the thread that nothing balances, so the spheres keep swinging apart until the threads are in one straight line through the support.
Distance =L+L=2L=2×2=4.0 m.
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