Question

What is the magnitude of the two identical charges with a force equal to 90 N and positioned 1 cm apart?​

Answer 1

that is magnitude force is always equal

Answer 2

According to Coulomb's law, The equation of force between point charges is

$F = \frac{q_{1}q_{2}}{4\piϵ_{0} {r}^{2} }$

Given,

Force F = 90N

Charges are identical

$q_{1} = q_{2} = q$

Distance r = 1cm = 0.01m

We know permitivity of vacuum

$ϵ_{0} = 8.85 \times {10}^{ - 12} F/m$

Putting the values into the equation,

$90 = \frac{ {q}^{2} }{4\pi \times 8.85 \times {10}^{ - 12 } \times (0.01)^{2} } \\ {q}^{2} = 90 \times 4\pi \times 8.85 \times {10}^{ - 12} \times (0.01)^{2} \\ {q}^{2} = 1 \times {10}^{ - 12} \\ q = {10}^{ - 6} C$