In a uniformly charged dielectric sphere, a very thin tunnel has been made along the diameter as shown in figure. A charge particle $-q$ having mass $m$ is released from rest at one end of the tunnel. For the situation described, mark the correct statement(s). (Neglect gravity.)

Consider two identical charges placed distance $2d$ apart, along the $x$-axis (see figure). The equilibrium of a positive test charge placed at point $O$ midway between them is,

For the situation shown in the figure (assume $r\gg$the length of the dipole) mark out the correct statement(s).

Two small balls $A$ and $B$ of positive charge $Q$ each and masses $m$ and $2m$, respectively, are connected by a non-conducting light rod of length $L$. This system is released in a uniform electric field of strength $E$ as shown. Just after the release (assume no other force acts on the system)