A parallel plate air capacitor of capacitance | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(D) Initially,the capacitor is charged to $q = CV$. When the cell is disconnected,the charge $q$ remains constant on the plates.After inserting the di

Vedclass · Accepted Answer

The charge on the capacitor is not conserved.

Vedclass · Answer

(D) Initially,the capacitor is charged to $q = CV$. When the cell is disconnected,the charge $q$ remains constant on the plates.After inserting the dielectric slab,the new capacitance becomes $C' = KC$.The potential difference between the plates becomes $V' = \frac{q}{C'} = \frac{CV}{KC} = \frac{V}{K}$. Thus,the potential difference decreases $K$ times.The initial energy stored is $U_1 = \frac{q^2}{2C} = \frac{1}{2}CV^2$.The final energy stored is $U_2 = \frac{q^2}{2C'} = \frac{q^2}{2KC} = \frac{U_1}{K}$. Thus,the energy decreases $K$ times.The change in energy is $\Delta U = U_2 - U_1 = \frac{q^2}{2KC} - \frac{q^2}{2C} = \frac{1}{2}CV^2\left(\frac{1}{K} - 1\right)$.Since the capacitor is disconnected from the cell,the charge $q$ on the plates remains constant (conserved). Therefore,the statement that the charge is not conserved is incorrect.

$A$ parallel plate air capacitor of capacitance $C$ is connected to a cell of emf $V$ and then disconnected from it. $A$ dielectric slab of dielectric constant $K,$ which can just fill the air gap of the capacitor,is now inserted in it. Which of the following is incorrect $?$

Similar Questions

Two point charges are placed at a distance $r$ in air,experiencing a force $F$. When they are placed in a medium with a dielectric constant $K$,at what distance will the force between them remain the same?

$A$ parallel plate air capacitor has capacitance $C_p$. It is equally filled with parallel layers of materials of dielectric constants $K_1$ and $K_2$. Now its capacity becomes $C_K$. The ratio $C_P$ to $C_K$ is

Consider a parallel plate capacitor of $10\,\mu F$ with air filled in the gap between the plates. Now,one half of the space between the plates is filled with a dielectric of dielectric constant $K = 4$,as shown in the figure. The capacity of the capacitor changes to.......$\mu F$.

$A$ parallel plate capacitor filled with oil of a dielectric constant $3$ between the plates has capacitance $C$. If the oil is removed,then the capacitance of the capacitor will be

Vedclass Test Series

Exam Paper Generator

Online Exam Module