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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 )

Correct answer

0

Step-by-step solution

In air: tan θ 2 = F m g = q 2 4 π ε 0 r 2 m g In water: tan θ 2 = F ' m g ' = q 2 4 π ε 0 ε r r 2 mg eff Equate both equations, we get ε 0 g = ε 0 ε r g 1 - 1 1 . 5 ⇒ ε r = 3

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