A vertical electric field of magnitude 4 . 9 × 10 5   N   C - 1 just prevents a water droplet…

A vertical electric field of magnitude 4.9×105 N C-1 just prevents a water droplet of a mass 0.1 g from falling. The value of charge on the droplet will be : (Given g=9.8 m s-2)
  1. 1.6×10-9C
  2. 2.0×10-9C
  3. 3.2×10-9C
  4. 0.5×10-9C

Solution

To balance gravitational force, electric force on the liquid drop should act in upward direction.

For translational equilibrium along vertical direction,

qE=mg

q=mgE=0.1×10-3×9.84.9×105=2.0×10-9C

Asked in: JEE Main 2022 (24 Jun Shift 1)

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