Question

In the area of the point charge q, we place a 0.2  μC  – charge so that a force of 5x10 -5  N applied on it due to the charge q. Find the electric field produced by this unknown charge q?  

Answer 1

By definition, the electric field strength at some point is the force exerted per unit positive electric charge at that point. Thus, if the charge $q$ apply the force $F = 5\times 10^{-5}N$ to the $q_2 = 0.2\mu C = 0.2\times 10^{-6}C$, it would apply the following force to the unit charge:

$$E = \dfrac{F}{q_2} = \dfrac{5\times 10^{-5}N}{0.2\times 10^{-6}C} = 250N/C$$

Answer. 250 N/C.