Question

solve numerical example
Two small spheres 18 cm apart have
equal negative charges and repel each
other with the force of 6x10^-8N. Find the
total charge on both spheres.​

Answer 1

Answer:

Explanation:

The force between two equal charges q separated by a distance r is given by

F=k\frac{q^2}{r^2}

where k is Coulomb's constant

k=9\times 10^9\text{ N-m}^2\text{C}^{-2}

Given r = 18 cm = 18\times 10^{-2} m

Force F=6\times 10^{-8} N

Thus from the equation

q^2=\frac{Fr^2}{k}

\implies q^2=\frac{6\times 10^{-8}\times (18\times 10^{-2})^2}{9\times 10^9}

\implies q^2=\frac{6\times 10^{-8}\times 18\times 18\times 10^{-4})}{9\times 10^9}

\implies q^2=6\times 18\times 2\times 10^{-21}

\implies q^2=21.6\times 10^{-20}

\implies q=\sqrt{21.6\times 10^{-20}}

\implies q=4.64\times 10^{-10} C