Charge $q$ is uniformly distributed over a thin half ring of radius $R$. The electric field at the centre of the ring is
$\frac{q}{{2{\pi ^2}{\varepsilon _0}{R^2}}}$
$\frac{q}{{4{\pi ^2}{\varepsilon _0}{R^2}}}$
$\frac{q}{{4\pi {\varepsilon _0}{R^2}}}$
$\frac{q}{{2\pi {\varepsilon _0}{R^2}}}$
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)
The equivalent capacitance between points $A$ and $B$ of the circuit shown will be
Two parallel metal plates having charges $+ Q$ and $-Q$ face each other at a certain distance between them. If the plates are now dipped in kerosene oil tank, the electric field between the plates will
A network of four capacitors of capacity equal to $C_1 = C,$ $C_2 = 2C,$ $C_3 = 3C$ and $C_4 = 4C$ are conducted to a battery as shown in the figure. The ratio of the charges on $C_2$ and $C_4$ is
The conducting spherical shells shown in the figure are connected by a conductor. The capacitance of the system is