Two charged particles of mass $1 \ g$ each are placed $1 \ m$ apart. If each of these possesses $1 \ fC$ (femto coulomb) of charge, then the dominant force of interaction between them is:

Two identical charges $+Q$ are kept fixed at some distance apart. $A$ small particle $P$ with charge $q$ is placed midway between them. If $P$ is given a small displacement $\Delta$,it will undergo simple harmonic motion if:

An empty thick conducting shell of inner radius $a$ and outer radius $b$ is shown in the figure. If it is observed that the inner face of the shell carries a uniform charge density $-\sigma$ and the outer surface carries a uniform charge density $+\sigma$, if the inner surface of the shell is earthed, then identify the correct statement(s).

The adjacent diagram shows a charge $+Q$ held on an insulating support $S$ and enclosed by a hollow spherical conductor. $O$ represents the centre of the spherical conductor,and $P$ is a point such that $OP = x$ and $SP = r$. The electric field at point $P$ will be

In free space,a particle $A$ of charge $1\,\mu C$ is held fixed at a point $P.$ Another particle $B$ of the same charge and mass $4\,\mu g$ is kept at a distance of $1\,mm$ from $P$. If $B$ is released,then its velocity at a distance of $9\,mm$ from $P$ is [ Take $\frac{1}{4\pi \varepsilon_0} = 9 \times 10^9\,N m^2 C^{-2}$ ]

$A$ particle of mass $m$ and charge $q$ is thrown in a region where uniform gravitational field and electric field are present. The path of the particle: