In the circuit, shown in the figure, the effective capacitance between $A$ and $B$ is......$\mu F$
$3$
$2$
$4$
$8$
Two identical small spheres carry charge of $Q_1$ and $Q_2$ with $Q_1>>Q_2.$ The charges are $d$ distance apart. The force they exert on one another is $F_1.$ The spheres are made to touch one another and then separated to distance $d$ apart. The force they exert on one another now is $F_2.$ Then $F_1/F_2$ is
Four charges are placed at the circumference of a dial clock as shown in figure. If the clock has only hour hand, then the resultant force on a charge $q_0$ placed at the centre, points in the direction which shows the time as:
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
Two conducting spheres of radii $r_1$ and $r_2$ have same electric fields near their surfaces. The ratio of their electric potentials is
A parallel plate capacitor of area $A$, plate separation $d$ and capacitance $C$ is filled with three different dielectric materials having dielectric constant $K_1,K_2$ and $K_3$ as shown. If a single dielectric material is to be used to have the same capacitance $C$ in this capacitor, then its dielectric constant $K$ is given by: ($A =$ Area of plates)