According to the question 
for equilibrium, net force on charge Q=0 ∴4πϵ01r2Qq+4πϵ01⋅σ(2r)2Q2=0 ⇒⇒⇒4πϵ01r2Q2Qq=−4πϵ01r24Qq=−4q=−4Q
A charge ' q ' is placed at the centre of the line joining two equal charges ' Q '. The system of three charges will be in equilibrium if ' q ' is equal to:
Held on 30 Apr 2013 · Verified 9 Jul 2026.
−Q/4
Q/4
−Q/2
Q/2
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