In equilibrium, Fe=Tsinθ mg=Tcosθ tanθ=mgFe=4πϵ0x2×mgq2 also tanθ≈sin=ℓx/2 Hence, 2ℓx=4πϵ0x2×mgq2 ⇒x3=4πϵ0mg2q2ℓ ∴x=(2πϵ0mgq2ℓ)1/3 Therefore x∝ℓ1/3
JEE Main 2013 — Physics Electromagnetism
Two balls of same mass and carrying equal charge are hung from a fixed support of length l. At electrostatic equilibrium, assuming that angles made by each thread is small, the separation, x between the balls is proportional to :
Held on 9 Apr 2013 · Verified 6 Jul 2026.
l
l2
l2/3
l1/3
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