Consider the arrangement shown in figure. The total energy stored is $U_1$ when key is closed. Now the key $K$ is made off (opened) and two dielectric slabs of relative permittivity ${ \in _r}$ are introduced between the plates of the two capacitors. The slab tightly fit in between the plates. The total energy stored is now $U_2$. Then the ratio of $U_1/U_2$ is
$\frac{{2{ \in _r}}}{{1\, + \, \in _r^2}}$
${ \in _r}$
$\frac{1}{{{ \in _r}}}$
$\frac{{{ \in _r}}}{{1\, + \, \in _r}}$
A parallel plate air capacitor is charged and then isolated. When a dielectric material is inserted between the plates of the capacitor, then which of the following does not change
While a capacitor remains connected to a battery and dielectric slab is applied between the plates, then
Write the types of dielectric and explain them. Give some examples of dielectric substance.
Assertion : The electrostatic force between the plates of a charged isolated capacitor decreases when dielectric fills whole space between plates.
Reason : The electric field between the plates of a charged isolated capacitance increases when dielectric fills whole space between plates.
Between the plates of a parallel plate condenser, a plate of thickness ${t_1}$ and dielectric constant ${k_1}$ is placed. In the rest of the space, there is another plate of thickness ${t_2}$ and dielectric constant ${k_2}$. The potential difference across the condenser will be