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Roll No. :
Date :
Time -
MM - 50
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The given figure shows a non-conducting semicircular rod. What is the direction of the net
electric field at point P due to the charge on the rod?
A uniform electric field E exists between two charged plates as shown in figure. What would be
the work done in moving a charge q along the closed rectangular path ABCDA?
The following graph shows the variation of charge Q, with voltage V, for two capacitors K and L.
In which capacitor is more electrostatic energy stored?
Figure shows two large metal plates, P1 and P2, tightly held against each other and placed
between two equal and unlike point charges perpendicular to the line joining them.
(i) What will happen to the plates when they are released?
(ii) Draw the pattern of the electric field lines for the system.
A thin straight infinitely long conducting wire having charge density λ is enclosed by a cylindrical
surface of radius r and length l, its axis coinciding with the length of the wire. Find the expression
for the electric flux through the surface of the cylinder.
The figure given below shows a uniformly charged non-conducting rod. What is the direction of
electric field at point P due to the charge on the rod?

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A small metal sphere carrying the charge +Q is located at the centre of a spherical cavity in a
large uncharged metal sphere
as shown in the figure.
Use the Gauss’s theorem to find the electric flux at points P1 and P2.
S1 and S2 are two hollow concentric spheres enclosing charge Q and 2Q respectively as shown
in figure.
(i) What is the ratio of the electric flux through S1 and S2?
(ii) How will the electric flux through the sphere S1 change, if a medium of dielectric constant 5 is
introduced in the space inside S1 in place of air?
A graph is drawn between some physical quantity x and r as shown below, where r is the
distance from the centre of a charged conducting sphere.
Now answer the following:
(a) Name the physical quantity x.
(b) At what point electric field is (i) maximum, and (ii) minimum?
A hemispherical surface lies as shown in an uniform electric field region. Find the net electric flux
through the curved surface if electric field is
(a) along x-axis, and
(b) along y-axis.
State Gauss’s law in electrostatics. A cube with each side a is kept in an electric field given by
, (as is shown in the figure) where C is

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a positive dimensional constant. Find out
(i) the electric flux through the cube, and
(ii) the net charge inside the cube
.
An uncharged comb after combing hair, when brought near the paper bits attracts them. Answer
the following:
(a) Does the mass of comb/paper bit get changed?
(b) Is paper bit still uncharged?
(c) What is the difference between the charging of a comb and the charging of the paper bits?
A thin metallic spherical shell of radius R carries a charge Q on its surface. A point charge is
placed at its centre
C and an other charge +2Q is placed outside the shell at a distance x from the centre as shown in
figure. Find (i) the force on the charge at the centre of shell and at the point A, (ii) the electric flux
through the shell.
Three concentric metallic shells A, B and C of radii a, b and c (a < b < c) have surface charge
densities + σ, – σ and + σ respectively as shown in the figure.
If shells A and C are at the same potential, then obtain the relation between the radii a, b, c.
Five identical horizontal square metal plates each of area A are placed at a distance d apart in
air and connected to the terminals A and B as shown in the figures (a) and (b). Find the effective
capacitance between the two terminals A and B.
Figure shows three circuits, each consisting of a switch and two capacitors initially charged as
indicated. After the switch has been closed, in which circuit (if any) will the charges on the left hand
capacitor (i) increase, (ii) decrease and (iii) remain same?

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(a) Two isolated metal spheres A and B have radii R and 2R respectively, and same charge q.
Find which of the two spheres have greater:
(i) capacitance and (ii) energy density just outside the surface of the spheres.
(b) (i) Show that the equipotential surfaces are closed together in the regions of strong field and far
apart in the regions of weak field. Draw equipotential surfaces for an electric dipole.
(ii) Concentric equipotential surfaces due to a charged body placed at the centre are shown.
Identify the polarity of the charge and draw the electric field lines due to it.
(a) Deduce the expression for the potential energy of a system of two charges q1 and q2 located
at and respectively in an external electric field.
(b) Three point charges, +Q, + 2Q and –3Q are placed at the vertices of an equilateral triangle ABC
of side l. If these charges are displaced to the mid-points A1, B1 and C1 respectively, find the
amount of the work done in shifting the charges to the new locations.
Derive the expression for the energy stored in a parallel plate capacitor of capacitance C with air
as medium between its plates having charges Q and where A is the area of each plate
and d is the separation between the plates.
How will the energy stored in a fully charged capacitor change when the separation between the
plates is doubled and a dielectric medium of dielectric constant 4 is introduced between the plates?

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