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JEE Main 2024 (30 Jan, Shift 2) · Electric Charge & Coulomb's Law

Electric Charge & Coulomb's Law question from JEE Main 2024 (30 Jan, Shift 2)

Q35JEE Main 2024 · 30 JAN · SHIFT 2Medium

Electric Charge & Coulomb's Law

Two identical charged spheres are suspended by strings of equal lengths. The strings make an angle of 37∘37^\circ with each other. When suspended in a liquid of density 0.7 g/cm30.7\text{ g/cm}^{3}, the angle remains same. If density of material of the sphere is 1.4 g/cm31.4\text{ g/cm}^{3}, the dielectric constant of the liquid is _______ (tan⁡37∘=34)\left(\tan 37^\circ = \frac{3}{4}\right)

Numerical answer type. Work it out, then open the answer.

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Answer: 2

  1. Same angle in air and liquid: Fmg=F/Kmg(1−σ/ρ)⇒K=ρρ−σ\dfrac{F}{mg} = \dfrac{F/K}{mg(1 - \sigma/\rho)} \Rightarrow K = \dfrac{\rho}{\rho - \sigma}.
  2. K=1.41.4−0.7=2K = \dfrac{1.4}{1.4 - 0.7} = 2
  3. Dielectric constant of the liquid =2= 2.
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