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A liquid drop having 6 excess electrons is kept stationary under a uniform electric field of 25.5 kVm ⁻¹ . The density of liquid is 1.26 10^3 ~kg ~m ⁻³ . The radius of the drop is (neglect buoyancy).

Options

  1. A4.3 10⁻⁷ ~m
  2. B7.8 10⁻⁷ ~m
  3. C0.078 10⁻⁷ ~m
  4. D3.4 10⁻⁷ ~m

Correct answer

B. 7.8 10⁻⁷ ~m

Step-by-step solution

F = qE =m g ( q =6 e =6 1.6 10⁻¹⁹ ) Density ( d )= mass volume = m 4 3 r ^3 or r^3= m 4 3 d Putting the value of d and m (= q E g ) and solving we get r =7.8 10⁻⁷ ~m

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