Question:

The electric field required to keep a water drop of mass in just to remain suspended, when charged with one electron:

Updated On: Jul 29, 2022
  • $ \text{em/g} $
  • $ \text{mg/e} $
  • $ \text{emg} $
  • $ \text{mg} $
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The Correct Option is B

Solution and Explanation

Here: mass of water drop $ =m, $ so, weight of water drop $ =mg $ so, $ mg= $ electrostatic force applied by the field $ mg=qE=eE\,\,\,\Rightarrow \,\,\,E=\frac{mg}{e} $
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Concepts Used:

Electric Field

Electric Field is the electric force experienced by a unit charge. 

The electric force is calculated using the coulomb's law, whose formula is:

\(F=k\dfrac{|q_{1}q_{2}|}{r^{2}}\)

While substituting q2 as 1, electric field becomes:

 \(E=k\dfrac{|q_{1}|}{r^{2}}\)

SI unit of Electric Field is V/m (Volt per meter).