Question

A point charge is placed 3 m from a 4 µC charge. What is the strength of the electric field on the point charge at this distance? (Round to the nearest whole number.)

Answer 1

The strength of the electric field generated by the charge is given by:
$E(r)=k \frac{q}{r^2}$
where
k is the Coulomb's constant
$q=4 \mu C=4 \cdot 10^{-6}C$ is the magnitude of the charge
$r=3 m$ is the distance at which we want to calculate the field

Substituting the numbers into the equation, we find
$E=(8.99 \cdot 10^9 Nm^2C^{-2}) \frac{4 \cdot 10^{-6} C}{(3 m)^2}=4000 N/C$

Answer 2

the answer is 4,000 newtons per coulomb on edge