Question

A ball has an electric charge of +1.5 × 10-9 coulombs. At what distance from the ball's center is the electric field strength equal to 5.8 × 105 newtons/coulomb?

Answer 1

F = kq1q2/r2
Where,
F - Coulomb Force
k - constant value which is equal to 8.98 × 10^9 newton square metre per square coulomb
q1 and q2 -  two electric charges
r - distance.

5.8 * 10^5 = 1.5 * 10^-9 / r^2
5.8 * 10^5 r^2 = 1.5*10^-9
r^2 = 0.0000258620
r = 0.0050854694

So the distance is equal to 5.09 x 10^-3