The strength of an electric field at 5.0 cm from a point charge is 100.0 N/C. What is the magnitude of the source charge? Show work so I understand how to do it.

3 answers

E=kQ/r^2
solve for Q, you have r, E
If I knew how to do it with formula I would have done it.
Rearrange the formula to calculate Q, using algebra. You get

Q = r^2*E/k

k = 8.99*10^9 N*m^2/C^2
(a constant of nature)
E = 100 N/C
r = 0.05 m

Just crank out the number. It will be in Coulombs.