Question

Two charges of magnitudes 5nC and -2nC are placed at points (2cm,0,0) and (x,0,0) in a region of free space where there is no other external field .If the electrostatic potential energy of whole system is -0.5mJ .What is the value of x

Answer 1

Answer:

x=2.018 cm

Explanation:

We have,

$q_1 =5nC \\ \\q_2=-2nC$

Electrostatic Potential Energy, U =-0.5mJ

Displacement, r = (x-2)cm.

Then, we have :

$U =\frac{kq_1q_2}{r}\\ \\=>-0.5mJ = \frac{9*10^9*5nC*-2nC}{(x-2)*10^{-2}}\\ \\=>0.5*10^{-3}=\frac{9*10^9*5*10^{-9}*2*10^{-9}}{(x-2)*10^{-2}}\\ \\=>(x-2) = 180*10^{-4}\\ \\=>x=2.018\:cm$

Hence, the value of x is 2.018cm.

And Position of Charge -2nC is (2.018cm,0,0).