Question

Two positively charged particles each of mass $1.7\times {10}^{-27}$ kg and carrying a charge of $1.6\times {10}^{-19}$ C are placed at a distance $r$ apart. If each one experiences a repulsive force equal to its weight, then $r$ is :

• A. $1.17m$
• B. $1.71m$
• C. $0.117m$
• D. $0.171m$

Answer 1

Answer: (C)

$0.117m$

The repulsive electrostatic force between the charges is given by,

$[F=(k\times q^2\left)/r^2\right]$

$[F=[9\times {10}^9\times (1.6\times {10}^{-19}{)}^2]/r^2]$

it is given that this force is equal to weight of the charge i.e. $[F=m\times g]$

$[9\times {10}^9\times (1.6\times {10}^{-19}{)}^2/r^2=1.7\times {10}^{-27}\times 9.8]$

$[r=0.117]$ m