EASY
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Statement 1: In order to fully charge a capacitor C to a potential difference of V, the energy supplied by the battery is CV2

Statement 2: The work done in moving a charge q=(CV) through a potential difference V is qV

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Important Questions on Electrostatics

EASY
A 10 μF capacitor is charged to 500 V and then its plates are joined together through a resistance of 10 Ω. The heat produced in the resistance is
MEDIUM

In the circuit given below, the capacitor C is charged by closing the switch S1 and opening the switch S2. After charging, the switch S1 is opened and S2 is closed, then the maximum current in the circuit

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MEDIUM

A capacitor of capacitance C is connected in series with a resistance R and DC source of emf E through a key. The capacitor starts charging when the key is closed. By the time the capacitor has been fully charged, what amount of energy is dissipated in the resistance R?

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HARD
A parallel plate capacitor having capacitance 12pF is charged by a battery to a potential difference of 10V between its plates. The charging battery is now disconnected and a porcelain slab of dielectric constant 6.5 is slipped between the plates. The work done by the capacitor on the slab is
MEDIUM
A capacitor with capacitance 5 μF is charged to 5 μC . If the plates are pulled apart to reduce the capacitance to 2 μF, how much work is done?
EASY
A circuit has a self-inductance of 1 H and carries a current of 2 A. To prevent spark, when the circuit is broken, a capacitor which can withstand 400 V is used. The least capacitance of the capacitor is,
EASY

The potential differences that must be applied across the parallel and series combination of 3 identical capacitors is such that the energy stored in them becomes the same. The ratio of potential difference in parallel to series combination is

EASY
The energy per unit volume for a capacitor having area A and separation d kept at potential difference V is given by
MEDIUM
A capacitor C is fully charged with voltage V0. After disconnecting the voltage source, it is connected in parallel with another uncharged capacitor of capacitance C2. The energy loss in the process after the charge is distributed between the two capacitors is :
MEDIUM
10 μF capacitor is fully charged to a potential difference of 50 V After removing the source voltage it is connected to an uncharged capacitor in parallel. Now the potential difference across them becomes 20 V. The capacitance of the second capacitor is :
EASY

In figure, charge on the capacitor is plotted against potential difference across the capacitor. The capacitance and energy stored in the capacitor are respectively.

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EASY
A parallel plate air capacitor has capacity C farad, potential V volt and energy E joule. When the gap between the plates is completely filled with dielectric
MEDIUM
A parallel plate capacitor has a uniform electric field E in the space between the plates. If the distance between the plates is d and the area of each plate is A, the energy stored in the capacitor is: ε0= permittivity of free space)
EASY
A 10 mF capacitor has been charged to a potential of 100 V. Suddenly if it explodes, the energy given out is
MEDIUM
A  6μF capacitor is charged from 10V to 20V. Increase in energy will be
MEDIUM

A capacitor of capacitance C=900 pF is charged fully by 100 V battery B as shown in figure (a). Then it is disconnected from the battery and connected to another uncharged capacitor of capacitance C=900 pF as shown in figure (b). The electrostatic energy stored by the system (b) is

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EASY
If the charge on a capacitor is increased by 2C, the energy stored in it increases by 44%. The original charge on the capacitor is (in C)
MEDIUM
A parallel plate capacitor has plate of length l, width w and separation of plates is d. It is connected to a battery of emf V. A dielectric slab of the same thickness d and of dielectric constant K=4 is being inserted between the plates of the capacitor. At what length of the slab inside plates, will the energy stored in the capacitor be two times the initial energy stored?
MEDIUM
The energy stored in the electric field produced by a metal sphere is 4.5 J. If the sphere contains 4 μC charge, its radius will be: Take:14π0=9×109 N m2 C-2
MEDIUM
If the capacitance of a nanocapacitor is measured in terms of a unit u,  made by combining the electronic charge e, Bohr radius a0, Planck's constant h and speed of light c then