$A$ long cylindrical shell carries positive surface charge $\sigma$ in the upper half and negative surface charge $-\sigma$ in the lower half. The electric field lines around the cylinder will look like the figure given in:

Two small spheres each carrying a charge $q$ are placed $r$ metre apart. If one of the spheres is taken around the other one in a circular path of radius $r$,the work done will be equal to

Five balls numbered $1$ to $5$ are suspended using separate threads. Pairs $(1, 2), (2, 4)$ and $(4, 1)$ show electrostatic attraction,while pairs $(2, 3)$ and $(4, 5)$ show repulsion. Ball $1$ must be:

Three point charges are placed at the corners of an equilateral triangle. Assuming only electrostatic forces are acting, which of the following statements is true?

The figure shows a nonconducting ring which has positive and negative charge non-uniformly distributed on it such that the total charge is zero. Which of the following statements is true?

$A$ charge $Q$ is uniformly distributed over the volume of an insulating sphere of radius $R$. $A$ thin metal shell of radius $b$ $(b > R)$ with a charge $-Q$ is placed around the sphere. The space between the sphere and the shell is filled with air. Which of the following graphs correctly represents the electric field $E$ as a function of distance $r$ from the center?