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

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

Problem

Two like point charges

q_1=+4\,\mu\text{C}

and

q_2=+1\,\mu\text{C}

are fixed in air on the

x

-axis at

x=0

and

x=0.12\,\text{m}

respectively. (i) Obtain an equation in

x

for the electric potential

V(x)

at a general point

P

on the

x

-axis measured from the origin. (ii) Determine all positions on the

x

-axis where the total potential equals

+3.0\times10^{5}\;\text{V}

. Indicate the region (left of both charges, between them, or to the right) in which each solution lies. (Take

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