Question

A charge +q is at the origin. A charge -2q is at x = 6.30 m on the +x axis.
(a) For what finite value of x is the electric field zero?
(b)or what finite values of x is the electric potential zero? (Note: Assume a reference level of potential V = 0 at r = ∞.)
Smallest value of x:

Largest value of x:



I m not sure really where to start with this.. any guidance would be appreciated.
bobpursley
a. add the E from each charge, set to zero.
k(q)/x^2+-2kq/(6-x)^2=0
(6-x)^2-2x^2=0
solve that quadratic for x.

b. Voltage=kq/x
kq/x-2kq/(6-x)=0
6-x-2x=0
x=2

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