Question

hi -- thank you for your help before-- that makes sense--
also, im stuck on this: if there is a negative2.5 microcoulomb charge 1 m away from a 6microcoulomb charge, then at what point (other than infinity) is the electric field = zero?
Sorry, i have no idea how to do this, i tried finding F using Kq1q2/ r^2 but im not sure what is next...or if that is even correct..?

Answer 1

WEll, E is a vector. If the charges are the same, between them the individual E are in opposite directions, so if at the right point, E adds to zero

k*2.5E-6/x^2 -k6E-6/(1-x)^2=0
solve for x.

notice it is a quadratic.

Answer 2

thank you!