Two point charges and are placed in air on the -axis at and respectively

PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

Two point charges

q_1=+3\,\mu\text{C}

and

q_2=-12\,\mu\text{C}

are placed in air on the

x

-axis at

x=0

and

x=0.16\,\text{m}

respectively. (i) Write an expression for the total electric potential

V(x)

at a general point

P

on the

x

-axis. (ii) Calculate the coordinate(s) of the point(s) on the

x

-axis where the total potential becomes zero. State clearly whether the point lies between the charges or outside the interval. (Take

\dfrac{1}{4\pi\varepsilon_0}=9\times10^9\,\text{N m}^2\text{C}^{-2}