JEE Main 2024 Physics question
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 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)
Answer: 3
Solution
tan(θ/2) = F/W. In water F becomes F/K and W becomes W(1 − 1/1.5) = W/3, so K = 3.