Q. A oil drop having a mass $4.8 \times 10^{- 10}$g and charge $2.4 \times 10^{- 18}$ C stands still between two charged horizontal plates separated by a distance of 1 cm. If now the polarity of the plates is changed, instantaneous acceleration of the drop is (g=$10\ {ms}^{- 2}$)
A) 5${\ ms}^{- 2}$
B) 10 $ms^{- 2}$
C) $15\ {ms}^{- 2}$
D) $20\ {ms}^{- 2}$
Explanation
(b) $a = \frac{F}{m}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \frac{qE}{m}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \frac{mg}{m}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ g\ \ = 10\ {ms}^{- 2}\ $
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Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.