# Question #109dc

Nov 10, 2015

$202.5 \text{N}$

#### Explanation:

Coulomb's Law gives us the force $F$ between two changes ${q}_{2}$ and ${q}_{2}$ separated by a distance $r$:

$F = \frac{1}{4 \pi {\epsilon}_{0}} . \frac{{q}_{1} \times {q}_{2}}{{r}^{2}}$

This simplifies to:

$F = k . \frac{{q}_{1} \times {q}_{2}}{{r}^{2}}$

Where $k = 9 \times {10}^{9} \text{m/F}$

This distance between the two spheres is taken as the distance between their two centres. So $r = 2 \times 0.2 = 0.4 \text{m}$

$\therefore F = \frac{9 \times {10}^{9} \times {\left(60 \times {10}^{- 6}\right)}^{2}}{{0.4}^{2}}$

$\therefore F = 202.5 \text{N}$