Question

1. Calculate the electric field strength 0.4m from a 0.0098C charge.

Answer 1

By definition, the electric field strength of a point charge is:

$$E = k\dfrac{q}{r^2}$$

where $q = 0.0098C$ is the charge, $r = 0.4m$ is the distance from the charge, $k = 9\times 10^9N\cdot m^2/C^2$ is Coulomb's constant. Thus, obtain:

$$E = 9\times 10^9\dfrac{0.0098}{0.4^2} \approx 5.5\times 10^8V/m$$

Answer. $5.5\times 10^8V/m$.