Question

Two point charges are placed on the x axis. The charge +4q is at x=3.00 m, and the -q charge
is at x=-3.00.

a) There is a point on the x axis between the two charges where the electric potential is zero. Where is this point?
Found it to be: -1.80m

b) The electric potential also vanishes in one of the following regions:
Region 1, 10.0m>x>3.00 m;
Region 2, -3.00m>x> -10.0.
Identify the appropriate region.
Found to be region 2.

c) Find the value of x referred to in part B.
Not sure how to do this part.

Answer 1

V=kq1/r1 + kq2/r2=k(+4/(x+3)-1/x-3) where x is between-3 and -10

solving
4(x-3)=1(x+3)
3x=15
x=5m, which in coordinate terms is x=-5.00