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JEE PHYSICS MCQ: ELECTRIC POTENTIAL AND CAPACITANCE

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Analyzing +4 | -1

A parallel plate capacitor of plate area

A

and plate separation

d

is charged to potential

V

and then the battery is disconnected. A slab of dielectric constant

k

is then inserted between the plates of the capacitors so as to fill the space between the plates. If

Q,E

and

W

denote respectively, the magnitude of charge on each plate, the electric field between the plates (after the slab is inserted) and work done on the system in question in the process of inserting the slab, then state incorrect relation from the following

View answer and explanation

Correct option: D

W = \frac{{{\varepsilon _0}A{V^2}}}{{2d}}\left( {1 - \frac{1}{k}} \right)

Option D is the incorrect relation because the work done should be negative, indicating work done *by* the system, not *on* the system.

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The potential at a point distance

x

\mu \mathrm{m}

) due to some charges situated on the

x

axis is given by

V(x)=\frac{20}{x^2-5} \mathrm{V}

. The electric field at

x=5 \mu \mathrm{m}

is given by: A parallel plate capacitor is connected to a 5V battery and charged. The battery is then disconnected and a glass slab is introduced between the plates. Then, the quantities that decrease are A conducting sphere of radius

R

is given a charge

Q

. The electric potential and the electric field at the centre of the sphere respectively are Two capacitors when connected in series have a capacitance of

3\mu F,\,

and when connected in parallel have a capacitance of

16\mu F

. Their individual capacities are Statement-1: If temperature is increased, the dielectric constant of a polar dielectric decreases whereas that of a non-polar dielectric does not change significantly.
Statement-2: The magniude of dipole moment of individual polar molecule decreases significantly with increase in temperature. An electric dipole when placed in a uniform electric field

E

will have minimum potential energy, if the positive direction of dipole moment makes the following angle with

E