Question

A charged particle P has a mass of ${10}^{-16}$kg and carries a charge of $4.9\times {10}^{-19}C$ . The intensity of the electric field to be applied on it, in vertically upward direction, so as to keep it at rest is :

• A. $1\times {10}^{3}N{C}^{-1}$
• B. $2\times {10}^{3}N{C}^{-1}$
• C. $3\times {10}^{3}N{C}^{-1}$
• D. $0.5\times {10}^{3}N{C}^{-1}$

Answer 1

The correct option is B $2\times {10}^{3}N{C}^{-1}$

To keep the particle in rest electric force must balance weight
$\Rightarrow Eq=mg$
$\Rightarrow E=\frac{{10}^{-16}\times 10}{4\cdot 9\times {10}^{-19}}$

$\Rightarrow E=2\cdot 04\times {10}^{3}N/C.$