HARD
JEE Main
IMPORTANT
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The region between two concentric spheres of radii 'a' and 'b', respectively (see figure), has volume charge density , where A is a constant and r is the distance from the centre. At the centre of the spheres is a point charge Q. The value of A such that the electric field in the region between the spheres will be constant, is:

(a)
(b)
(c)
(d)

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Important Questions on Electrostatics
HARD
JEE Main
IMPORTANT
A combination of capacitors is set up as shown in the figure. The magnitude of the electric field, due to a point charge Q (having a charge equal to the sum of the charges on the and capacitors), at a point distant 30 m from it, would equal:


HARD
JEE Main
IMPORTANT
Within a spherical charge distribution of charge density N equipotential surfaces of potential are drawn and have increasing radii respectively. If the difference in the radii of the surfaces is constant for all values of then :

MEDIUM
JEE Main
IMPORTANT
Figure shows a network of capacitors where the number indicates capacitances in micro Farad. The value of capacitance C if the equivalent capacitance between point A and B is to be is :

EASY
JEE Main
IMPORTANT
Shown in the figure are two point charges and inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If is the surface charge on the inner surface and net charge on it and the surface charge on the outer surface and net charge on it then:


HARD
JEE Main
IMPORTANT
A thin disc of radius has a concentric hole of radius in it (see figure). It carries uniform surface charge on it. If the electric field on its axis at a height from its centre is given as then the value of is

MEDIUM
JEE Main
IMPORTANT
In the given circuits and , switches and are closed at and kept close for a long time. The variation of currents in the two circuits for are shown in the options. (Figures are schematic and not drawn to scale.)


MEDIUM
JEE Main
IMPORTANT
If the capacitance of a nanocapacitor is measured in terms of a unit , made by combining the electronic charge , Bohr radius Planck's constant and speed of light then

HARD
JEE Main
IMPORTANT
In the given circuit, charge on the capacitor changes as C is varied from to . as a function of 'C' is given properly by: (figures are drawn schematically and are not to scale)

