Embibe Experts Solutions for Exercise 7: EXERCISE 1.7

The magnitude of the each of two opposite charges that form an electric dipole is increased by a factor of $5$ while the separation between the charges is tripled. What is the change in magnitude of the torque on the dipole in a uniform field?

Find the dipole-moment of system

Two molecule each with permanent dipole moment $\overrightarrow{p}$ are aligned as shown. Calculate the force between the molecules if they are separated by a distance that is large compared with the dimension of the dipoles.
[Hint : The relation $(1+x{)}^{-2}\cong 1-2x+3x^2-\dots \dots$ for small $x$ is useful].

Charges $q,-q$ and $q$ coulomb are placed at the points $\left(-\hat{i}+\hat{j}+\hat{k}\right),\left(\hat{i}-\hat{j}+\hat{k}\right)$ and $\left(\hat{i}+\hat{j}-\hat{k}\right)$ respectively.
The $x$ - component of electric field at the origin will be

Two pith balls each with mass $m$ are suspended from insulating threads. When the pith balls are given equal positive charge $Q$, they hang in equilibrium as shown. We now increase the charge on the left pith ball from $Q$ to $2Q$ while leaving its mass essentially unchanged. Which of the following diagrams best represents the new equilibrium configuration?