Q.

Two identical charged spheres are suspended by strings of equal lengths. The strings make an angle θ with each other. When suspended in water, the angle remains the same. If the density of the material of the sphere is 1.5 g/cc, the dielectric constant of water will be ______.             

(Take density of water = 1 g/cc)                                  [2024]


Ans.

(3)

tanθ=KQ2(2lsinθ)2×ρvg     ...(i)

tanθ=KQ2ε(2lsinθ)2×(ρv-ρwv)g       ...(ii)

Compare (i) and (ii)

ε(ρv-ρwv)g=ρvg

ε=1.51.5-1=1.50.5=3