Two charges of -5×10^-9 C and -1.5×10^-9 C are separated by a distance of 43cm. Find the equilibrium position for a third charge of +1.1×10^-8 C by identifying its distance from the first charge q1.

Respuesta :

Solution

In this question we have given

Charge,[tex]q_{1}=-5\times 10^-9C[/tex]

Charge,[tex]q_{2}=-1.5\times 10^-9C[/tex]

Charge,[tex]q_{3} =1.1\times 10^-8C[/tex]

Distance between Charge [tex]q_{1}[/tex] and [tex]q_{2}[/tex],d=43cm=.43m

Let the distance between charge [tex]q_{1}[/tex] and [tex]q_{3} [/tex], is x

Therefore,distance between charge [tex]q_{2}[/tex] and [tex]q_{3} [/tex], will be=(.43-x)

We know By Couloms law, Force on Charge [tex]q_{3}[/tex] due to charge [tex]q_{1}[/tex] which are seperated by distance d is given by following equation

[tex]F_{1}=\frac{k\times q_{1}q_{2}}{d^2}[/tex]............(1)

Here, K=[tex]9\times 10^9 Nm^2C^-2[/tex]

Therefore,

Force on Charge [tex]q_{3}[/tex] due to charge [tex]q_{1}[/tex]

[tex]F_{1}=-\frac{k\times 5\times 10^-9C\times 1.1\times 10^-8C}{x^2}[/tex]..(2)

Similarly,

Force on Charge [tex]q_{3}[/tex] due to charge [tex]q_{2}[/tex]

[tex]F_{2}=-\frac{k\times 1.5\times 10^-9C\times 1.1\times 10^-8C}{(.43-x)^2}[/tex]..(2)

In equilibrium condition,

[tex]F_{1} =F_{2}[/tex]

[tex]-\frac{k\times 5\times 10^-9C\times 1.1\times 10^-8C}{x^2}=-\frac{k\times 1.5\times 10^-9C\times 1.1\times 10^-8C}{(.43-x)^2}[/tex]

[tex]\frac{5\times 10^-9C}{x^2}=\frac{1.5\times 10^-9C}{(.43-x)^2}[/tex]

[tex]5\times 10^-9C \times (.43-x)^2=1.5\times 10^-9C\times (x)^2[/tex]

[tex]3.5x^2-4.3x+.9245=0[/tex]

on solving we get

x=.277m

0r x=28cm

The distance between charge [tex]q_{1}[/tex] and [tex]q_{3} [/tex], is 28cm