Five balls marked a to $e$ are suspended using separate threads. Pairs $(b, c)$ and $(d, e)$ show electrostatic repulsion while pairs $(a, b),(c, e)$ and $(a, e)$ show electrostatic attraction. The ball marked a must be
Negatively charged
Positively charged
Uncharged
Any of the above is possible
A point charge $q$ is placed at a distance $\frac{a}{2}$ directly above the centre of a square of side $a$ . The electric flux through the square is
The potential $V$ is varying with $x$ and $y$ as $V = \frac{1}{2}({y^2} - 4x)\,volts$ The field at $(1\,m,\,1\,m)$ is
The plates of a parallel plate capacitor are charged up to $100\, volt$ . A $2\, mm$ thick plate is inserted between the plates, then to maintain the same potential difference, the distance between the capacitor plates is increased by $1.6\, mm$ . The dielectric constant of the plate is
Find flux related to shaded face $BCGF$
Four capacitors of capacitance $10\, \mu\, F$ and a battery of $200\,V$ are arranged as shown. How much charge will flow through $AB$ after the switch $S$ is closed?