Electric field due to a point charge is given by
[tex]E = \frac{kq}{r^2}[/tex]
here given that
[tex]k = 9*10^9[/tex]
[tex]q = 20\mu C[/tex]
[tex]r = 20 cm = 0.20 m[/tex]
Now electric field is given by
[tex]E = \frac{9*10^9 * 20 * 10^{-6}}{0.20^2}[/tex]
[tex]E = 4.5 * 10^6 N/C[/tex]
