Question

A positive charge of 6.0 × 10-4 C is in an electric field that exerts a force of 4.5 × 10-4 N on it. What is the strength of the electric field?

Answer 1

The force F produced by an electric field of intensity E on a charge of magnitude q is given by
$F=qE$
In our problem, we know the magnitude of the charge ($q=6.0 \cdot 10^{-4}C$) and of the force ($F=4.5 \cdot 10^{-4}N$), so we can find the intensity of the electric field:
$E= \frac{F}{q}= \frac{4.5 \cdot 10^{-4}N}{6.0 \cdot 10^{-4}C}=0.75 NC^{-1}$