JEE Main 2021PhysicsDual Nature of MatterHardMCQ

JEE Main 2021 — Dual Nature of Matter Question with Solution

JEE Main 2021 (18 Mar Shift 1)

Question

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.

Choose an option

Show full solutionCorrect option: B
Correct answer
B1.73×1010

Step-by-step explanation

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.

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About this question

This is a previous-year question from JEE Main 2021, covering the Dual Nature of Matter chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.