A parallel plate capacitor is made of two square parallel plates of area $A$ , and separated by a distance $d <  < \sqrt A $ . The capacitor is connected to a battery with potential $V$ and allowed to fully charge. The battery is then disconnected.  A square metal conducting slab also with area $A$ but thickness $\frac {d}{2}$ is then fully inserted between the plates, so that it is always parallel to the plates. How much work has been done on the metal slab by external agent while it is being inserted?

  • A

    $ + \frac{1}{4}\,\frac{{{ \in _0}A}}{d}{V^2}$

  • B

    $ - \frac{1}{2}\,\frac{{{ \in _0}A}}{d}{V^2}$

  • C

    $ + \frac{1}{2}\,\frac{{{ \in _0}A}}{d}{V^2}$

  • D

    $ - \frac{1}{4}\,\frac{{{ \in _0}A}}{d}{V^2}$

Similar Questions

A $60\; pF$ capacitor is fully charged by a $20\; \mathrm{V}$ supply. It is then disconnected from the supply and is connected to another uncharged $60 \;pF$ capactior is parallel. The electrostatic energy that is lost in this process by the time the charge is redistributed between them is (in $nJ$)

  • [JEE MAIN 2020]

A parallel plate capacitor carries a charge $q$. The distance between the plates is doubled by application of a force. The work done by the force is

If initial charge on all the capacitors were zero, work done by the battery in the circuit shown is ........... $mJ$

The energy stored in a condenser is in the form of

A capacitor is charged to $200\, volt$ it has $0.1$ coulomb charge. When it is discharged, energy will be.....$J$