(i) `2T cos theta =W, T sin theta=F`
or `(tan theta)/(2)=F/W or F=W(tan theta)/2`
or, `(q^2)/(4 pi epsilon_(0)(2x)^(2))=(W tan theta)/(2)` or `q=sqrt(8W tan theta pi epsilon_(0)x^(2))`
(ii) `T cos theta+mg=B implies (W)/(2) + V(rho_(He))g=Vrho_(a)g`
or `V=(W)/(2(rho_(a)-rho_(He))g)`.