An oil drop of the radius 2   mm with a density 3   g cm - 3 is held stationary under a constant…

An oil drop of the radius 2 mm with a density 3 g cm-3 is held stationary under a constant electric field 3.55×105 V m-1 in the Millikan's oil drop experiment. What is the number of excess electrons that the oil drop will possess? consider g=9.81 m s-2.
  1. 48.8×1011
  2. 1.73×1010
  3. 17.3×1010
  4. 1.73×1012

Solution

qE=Mg⇒neE=ρ43πr3×g
⇒n×1.6×10-19×3.55×105=3×103×43×π×2×10-33×9.81
⇒n=173×10(3-9-5+19)⇒n=1.73×1010.

Asked in: JEE Main 2021 (18 Mar Shift 1)

Practice more Dual Nature of Matter questions on Aicharya