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A uniformly charged solid sphere of radius R has potential V0 (measured with respect to ) on its surface. For this sphere the equipotential surfaces with potentials 3V02,5V04,3V04 and V04 have radius R1, R2, R3 and R4, respectively. Then

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Important Questions on Electrostatics

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JEE Main/Advance
IMPORTANT

The region between two concentric spheres of radii a and b, respectively (see figure), has volume charge density ρ=Ar, 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

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MEDIUM
JEE Main/Advance
IMPORTANT
An electric dipole has a fixed dipole moment p , which makes angle θ with respect to  x-axis. When subjected to an electric field E1=Ei^ , it experiences a torque T1=τk^. When subjected to another electric field E2=3E1j^ it experiences a torque T2=-T1. The angle θ is
MEDIUM
JEE Main/Advance
IMPORTANT
Three concentric metal shells A, B and C of respective radii a,b and c(a<b<c) have surface charge densities +σ, σ and +σ, respectively. The potential of shell B is,
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JEE Main/Advance
IMPORTANT

(i) Three equal charges q0 each are placed at three corners of an equilateral triangle of side a. Find out force acting on one of the charge due to other two charges?

(ii) In the above question, if one of the charge is replaced by negative charge then find out force acting on it due to other charges?

(iii) Repeat the part (i) if magnitude of each charge is doubled and side of triangle is reduced to half.

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JEE Main/Advance
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A solid sphere of radius R is uniformly charged with charge density ρ in its volume. A spherical cavity of radius R2 is made in the sphere as shown in the figure. Find the electric potential at the centre of the sphere.

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JEE Main/Advance
IMPORTANT

A uniform surface charge of density σ is given to a quarter of a disc extending up to infinity in the first quadrant of x-y plane. The centre of the disc is at the origin O. Find the z-component of the electric field at the point (0, 0, z) and the potential difference between the points (0, 0, d) & (0, 0, 2d).

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JEE Main/Advance
IMPORTANT
A charged ball of mass 5.88×104  kg is suspended from two silk strings of equal lengths so that the strings are inclined at 90° with each other. Another ball carrying a charge which is equal in magnitude but opposite in sign of the first one is placed vertically below the first one at a distance of 4.2×10-2 m.Due to this, the tension in the strings is doubled. Determine the charge on the ball and the tension in the strings after electrostatic interaction. (g=9.8 m s-2)
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JEE Main/Advance
IMPORTANT
A charge of 16×109 C is fixed at the origin of coordinates. A second charge of unknown magnitude is at x=3 m, y=0 and a third charge of 12×109 C is at x=6 m, y=0. What is the value of the unknown charge if the resultant field at x=8 m, y = 0 is 20.25 N C-1 directed towards positive x-axis