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NEET 2021
Exam
NEET
Year
2021
Subject
Physics
Chapter
Electrostatics

NEET 2021 · Physics · Electrostatics

Twenty seven drops of same size are charged at 220V each. They...

Twenty seven drops of same size are charged at 220V220V each. They combine to form a bigger drop. Calculate the potential of the bigger drop.

Options

  1. A660V660V
  2. B1320V1320V
  3. C1980V1980V
  4. D1520V1520V

Correct answer

C. 1980V1980V

Step-by-step solution

The radius of the bigger drop will be 43\piR3=27×43\pir3⇒R=3r\dfrac{4}{3}\piR^{3} = 27 \times \dfrac{4}{3}\pir^{3} ⇒ R = 3r,~ the potential of the small drop,& V=KqrV = \dfrac{Kq}{r}. The potential of the big drop Q=nq,V′=KQR⇒V′=KnqRQ = nq, V ' = \dfrac{KQ}{R} ⇒ V ' = \dfrac{Knq}{R}

As we know,V′=n2/3V=(27)2/3×220=1980VV{'}_{ } = n^{2 / 3}V= ( 27{)}^{2 / 3} \times 220= 1980V

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