Question

A -10.0/rmnC point charge and a +20.0/rmnC point charge are 15.0/rmcm apart on thex-axis.

What is the electric potential at the point on the x-axis where the electric field is zero?

What is the magnitude of the electric field at the point on the x-axis, between the charges, where the electric potential is zero?

Answer 1

Let electric field is Zero at x from -10nC

Distance from 20nC is x+0.15.

Thus, balancing the electric field:

K*20*^-9/(x+0.15)^2=k*10*10^-9/X^2

x^2/(x+0.15)^2 = 1/2

x/x+0.15 = √1/2

0.293x= 0.1061

x=0.36225 m from-10nC

Electric Potential:

P=K*20*^-9/(0.36225+0.15) -k*10*10^-9/0.36225

= 102.944 V

Let electric potential is Zero at x from -10nC

Distance from 20nC is x+0.15.

Thus,

K*20*^-9/(x+0.15)-k*10*10^-9/X=0

20*^-9/(x+0.15)=10*10^-9/X

x/(x+0.15) = 1/2

0.5x= 0.075

x=0.15 m from-10nC

Electric Field:

E=K*20*^-9/(0.15+0.15)^2-k*10*10^-9/.15^2

= -2000 N/C