Three point charges q, q and -2 q are placed at corners of an equilateral triangle of side ' L &

English

Gujarati

Hindi

2. Electric Potential and Capacitance

medium

Three point charges $q, q$ and $-2 q$ are placed at the corners of an equilateral triangle of side '$L$'. Calculate work done by extemal force in moving all the charges far apart without acceleration

A

$\frac{1}{4 \pi \varepsilon_0} \frac{3 q^2}{L}$

B

$-\frac{1}{4 \pi \varepsilon_0} \frac{3 q^2}{L}$

C

$\frac{1}{4 \pi \varepsilon_0} \frac{5 q^2}{L}$

D

$-\frac{1}{4 \pi \varepsilon_0} \frac{5 q^2}{L}$

Solution

(a)

$U=\frac{k(q)(-2 q)}{L}+\frac{k(q)(q)}{L}+\frac{k(q)(-2 q)}{L}$

$U=\frac{-3 k q^2}{L}$

$U_{\infty}=0$

$W_{\text {ost }}=U_{-}-U=\frac{3 k q^2}{L}$

Standard 12

Physics

Share

Similar Questions

${\rm{ }}1\,ne\,V{\rm{ }} = {\rm{ }}……\,J.$ (Fill in the gap)

easy

Obtain equation of electric energy of a single charge.

medium

The diagram shows three infinitely long uniform line charges placed on the $X, Y $ and $Z$ axis. The work done in moving a unit positive charge from $(1, 1, 1) $ to $(0, 1, 1) $ is equal to

normal

A bullet of mass $m$ and charge $q$ is fired towards a solid uniformly charged sphere of radius $R$ and total charge $+ q$. If it strikes the surface of sphere with speed $u$, find the minimum speed $u$ so that it can penetrate through the sphere. (Neglect all resistance forces or friction acting on bullet except electrostatic forces)

normal

Positive and negative point charges of equal magnitude are kept at $\left(0,0, \frac{a}{2}\right)$ and $\left(0,0, \frac{-a}{2}\right)$, respectively. The work done by the electric field when another positive point charge is moved from $(-a, 0,0)$ to $(0, a, 0)$ is

normal

(IIT-2006)