Question

two identical charged spheres are suspendedby string of equal length .each string makes an angle theta with the vertical .when suspended in a liquid sigma =0.8 gm/cc the angle remain same what is the dielectric constant of a liquid
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Answer 1

Explanation:

Explanation :



tanθ=qEmg=constanttanθ=qEmg=constant

kq2d2mg=tan300kq2d2mg=tan300

tan300=kq2d2mg=kq21.5Vgd2tan300=kq2d2mg=kq21.5Vgd2 [V is volume of sphere]     ---1

When suspended in liquid :



tan300=14π∈q2d21(mg−σVg)tan300=14π∈q2d21(mg−σVg)  -----2

=14π∈0Kq2d2gV(1.5−0.5)=14π∈0Kq2d2gV(1.5−0.5)

from1 and 2 we get

kq2d2gVK=kq21.5Vgd

Answer 2

Cool mate......

Initially, the forces acting on each ball are (i) Tension T (ii) Weight mg (iii) Electrostatic force of repulsion F For its equilibrium along vertical, Tcosθ = mg ...(i) and along horizontal, Tsinθ = F ...(ii) Dividing equation (ii) by (i), we get tanθ = F/mg   ...(iii) When the balls are suspended in a liquid of density σ and dielectric constant K, the electrostatic force will become (1/K) times, i.e. F′ = (F/K)....

Hope it helps......