Q.

Two identical charged spheres are suspended by string of equal lengths. The string make an angle of 37° with each other. When suspended in a liquid of density 0.7 g/cm3, the angle remains same. If density of material of the sphere is 1.4 g/cm3, the dielectric constant of the liquid is (tan37o=34) ______________ .       [2024]


Ans.

(2)

tanθ=Femg                             ...(1)

tanθ=Fe/K(mg-B)                  ...(2)

FeK(mg-B)=Femg

K(mg-B)=mg

K(σmVg-ρVg)=σmVg

Vkg[1.4-0.7]=1.4kg

K=1.40.7=2