Download Electrostatics

AL-MC-Electrostatics / p.1
1.
(88-I-31)
3.
(89-I-25)
Two large metal plates A, B are oppositely charged
The diagram shows points of equal potential joined
and placed a small distance apart. A piece of metal
as equipotential lines. Which of the following
M is placed centrally between the plates. Which of
statements is/are correct?
the following graphs shows the variation of electric
field intensity E from A to B?
(1)
The electric field at P is in a direction
tangential to the line passing through P.
(2)
The electric field is the same at the points P
and Q.
(1)
Work has to be done in moving an electron
from point P to point R.
2.
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
(88-I-33)
4.
(89-I-26)
An isolated spherical conductor of radius r is
charged to a potential V. The total electrical energy
stored is
A potential difference V is maintained between
plates X and Y, separated by a distance h. A
particle of mass m and positive charge q enters the
region between X and Y through the hole H with
negligible velocity. If it makes no collision on the
way, it will strike X with kinetic energy
A.
mgh.
B.
qV.
C.
qV + mgh.
D.
qV – mgh.
E.
mgh – qV.
A.
V 2 /(80 r ).
B.
V 2 /( 40 r ).
C.
V 2 /( 20 r ).
D.
V 2  (20 r ).
E.
V 2  (40 r ).
AL-MC-Electrostatics / p.2
5.
(89-I-30)
The arrangement above shows two concentric
hollow metal spheres of inner radius b and outer
radius a. A charge + Q is given to the inner sphere
and the outer sphere is earthed. What is the work
done in bringing a small positive charge q from
infinity to the surface of the inner sphere?
A particle carrying negative charge is free to move
in a uniform electric field E. If the particle starts
with a certain velocity from points X, which of the
paths shown could represent the route which the
particle would follow from X to Y?
A.
I and II only
B.
I and IV ony
C.
II and III only
D.
III and IV only
E.
I, II, III and IV
8.
6.
A.
zero
B.
qQ /( 40 a)
C.
qQ /( 40b)
D.
qQ /40 a  b 
E.
qQ(1/ b  1/ a) /( 40 )
(90-I-29)
(90-I-27)
A light conducting sphere is hanged from a long
insulating thread between oppositely charged metal
plates connected to a high voltage supply. If the
sphere is given a positive charge, it will
A.
move to the positive plate and stick to
it.
B.
move to the negative plate and stick to
it.
C.
remain still.
D.
oscillate, touching each plate in turn,
beginning with the negative plate.
E.
oscillate, touching each plate in turn,
beginning with the positive plate.
7.
(90-I-28)
A uniformly charged wire has the form of a
P1 and P2 are two
circular loop of radius b.
points on the axis of the loop.
b from the loop centre and
from the loop centre. At
are
P1 is at a distance
P2 is at a distance 2 b
P1 , P2 , the potentials
V1 ,V2 respectively. V2 /V1 is equal to
A.
1/3
B.
2/5
C.
1/2
D.
E.
2/ 5
4
AL-MC-Electrostatics / p.3
9.
(91-I-31)
Which of the graphs below best represents the
variation of electrical potential V with distance r
from the centre of a charged hollow metal sphere
of external radius a?
12.
10. (92-I-27)
(93-I-29)
A positively-charged metal sphere A of radius a is
How do the two physical quantities below change
joined by a conducting wire to an uncharged metal
along the direction indicated by an electric field line
sphere B of radius b placed far away from the first
from a point positive charge?
sphere. The ratio of the surface charge density on
sphere A to that on sphere B is
(1)
electric field intensity E
(2)
potential V
A.
b/a
B.
b2/a2
A.
Only E will increase
C.
a/b
B.
Only V will increase
D.
a2/ b2
C.
Both E and V will increase
D.
Both E and V will decrease
E.
b/a
E.
Both E and V will remain constant
11. (93-I-28)
An uncharged metal sphere is placed in a uniform
electric field. Which of the following best represents
the electric field pattern around the metal sphere?
AL-MC-Electrostatics / p.4
13. (93-I-35)
15. (94-IIA-24)
Two insulated parallel metal plates are connected to
X, Y are two different points in an electric field. A
the terminals of an EHT. When a charged
small charged object is released from rest at X.
aluminium foil strip is placed between the plates,
Which of the following conditions would ensure that
deflection of the foil is observed as shown.
the charged object will NOT pass through Y?
A.
The electric field at Y is zero.
B.
The electric field at Y is stronger than
that at X.
C.
The electric field between X and Y is
not zero.
D.
The electric potentials at X and Y are
equal.
E.
Which of the following statements is/are true?
The electric potential difference
between X and Y is not zero.
(1)
The charge on the foil is negative.
(2)
Deflection of the foil increases if the
Which of the following pairs of physical quantities
separation between the plates decreases.
is/are both scalars?
(3)
16. (94-IIA-25)
When moving the foil towards the positive
plate, the deflection of the foil increases.
(1)
work done and electric field intensity
(2)
pressure and force
(3)
charge and electric potential
A.
(1) only
B.
(3) only
C.
(1) and (2) only
A.
(1) only
D.
(2) and (3) only
B.
(3) only
E.
(1), (2) and (3)
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
14. (94-IIA-23)
A 10 W light bulb gives a certain illumination on a
surface 1.5 m away. At what distance would a 40 W
light bulb give the same illumination? (You may
regard a light bulb as a point source)
A.
1.5 m
B.
3.0 m
C.
6.0 m
D.
12.0 m
E.
24.0 m
AL-MC-Electrostatics / p.5
17. (94-IIA-27)
19.
(95-IIA-27)
The electric potential energy of a system of charges
at infinitely large distances from one another is
taken to be zero. What is the electric potential
energy stored in a system of four charges, each of
A, B, C, D are four points on a straight line as shown.
+1 C, placed at the vertices of a square with length
A point charge +Q is fixed at A. When another point
of side 1 m? (  o = permittivity of vacuum)
charge –Q is moved from B to C, which of the
A.
B.
C.
D.
E.
3
following quantities will increase?
(1)
 o
charges.
(2)
1
1
(2 
)
o
2
(3)
The electric potential at the point D.
A. (1) only
 o
B. (3) only
C. (1) and (2) only
5
D. (2) and (3) only
4 o
4o
The magnitude of the electric field strength
at the point D.
1
1
The electric potential energy of the system of
E. (1), (2) and (3)
(4  2 )
20. (96-IIA-16)
The straight lines in the diagram represent electric
field lines. Which of the following statements about
18. (95-IIA-26)
this electric field is/are correct?
Two uncharged metal spheres, A and B, supported
by insulating stands are placed side by side but not
touching each other. A student places a
positively-charged rod near sphere A and he touches
sphere B with his finger momentarily. When the rod
is removed afterwards, what are the signs of the
(1)
charges induced on the spheres?
A stationary negative charge placed at Q
tends to move to P.
(2)
The electric field strength at P is stronger
than that at Q.
Sphere A
Sphere B
A.
positive
neutral
B.
negative
negative
C.
negative
neutral
D.
neutral
positive
A.
(1) only
E.
neutral
negative
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(3)
Work has to be done in moving a negative
charge from R to P.
AL-MC-Electrostatics / p.6
21. (96-IIA-23)
(1)
the mass of the charged particle.
Five identical point charges, each of charge Q, are
(2)
The width of the gap.
fixed evenly on a circle of radius r. How much work
(3)
The potential difference between the plates.
has to be done to bring another point charge Q from
infinity to the centre of the circle?
A.
(1) only
(  0 = permittivity of free space)
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
A.
B.
C.
zero
5Q
4 0 r
24. (98-IIA-22)
Which of the following graphs shows correctly the
5Q 2
40 r
D.
5Q 2
40 r 2
E.
5Q
40 r 2
relationship between the energy E stored in an
isolated conducting sphere and the charge Q on it?
22. (97-IIA-22)
A metal sphere is charged to a potential of 100 V.
If the charge density on its surface is
6.0 x10 9 Cm 2 , find the radius of the sphere.
(Given : permittivity of free space =
8.85 x10 12 Fm 1 )
A.
0.04 m
25.
(99-IIA-21)
B.
0.15 m
Which of the following statements about electric
C.
0.21 m
field lines is incorrect?
D.
0.35 m
E.
0.60 m
A.
They are closest where the field is
strongest.
23. (97-IIA-28)
B.
A charged particle is accelerated across the gap
between two parallel metal plates maintained at a
equipotential lines.
C.
certain potential difference in a vacuum. Assuming
there is no gravitational force, the energy acquired
They are always perpendicular to
They always point from high electric
potential to low electric potential.
D.
Work has to be done in moving an
by the charged particle in crossing the gap depends
electron along the direction of a field
on
line.
E.
They tend to attract one another.
AL-MC-Electrostatics / p.7
26.
(00-IIA-21)
28.
(00-IIA-26)
Two parallel plates are connected to an E.H.T. of
4.5 kV. Electric breakdown occurs when the
separation of the plates is reduced to 1.5 mm.
In the above arrangement, two small test charges
Estimate the maximum acceleration of an electron
+q and +2q are brought from infinity to the
between the plates.
positions shown. The two charges are collinear
(Given: charge of an electron = 1.6  10
with another charge +Q and their mutual
mass of an electron =
separation is d. Which of the following statements
19
C;
9.1  10 31 kg )
is/are correct?
A.
(1)
(2)
Charge +q is at a higher potential than
B.
charge +2q.
C.
The work done in bringing the charges +q
D.
and +2q from infinity to their respective
E.
4.0  10 7 m s-2
1.0  10 9 m s-2
1.2  1012 m s-2
1.6  1015 m s-2
5.3  1017 m s-2
positions is the same.
(3)
The potential energy of the system would
increase if d decreases.
29.
(01-IIA-20)
Two insulated uncharged metal spheres X and Y are
in contact with each other. A positively charged rod
27.
A.
(1) only
is brought near X without any contact while sphere
B.
(3) only
X is earthed as shown.
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(00-IIA-22)
At steady state, which of the following descriptions
is/are correct?
(1)
Sphere X gains electrons.
(2)
Sphere Y loses electrons.
(3)
Sphere X acquires a negative electric
The figure shows a pattern of electric field lines in
which P, Q and R are points marked on one of the
field lines with PQ = QR. If the potential at P is
potential.
(4)
Sphere Y acquires a positive electric
potential.
0 V, which of the following can give the possible
potentials at Q and at R?
Potential at Q
Potential at R
A.
B.
C.
-200 V
-200 V
-200 V
-450 V
-400 V
-350 V
D.
+200 V
+350 V
E.
+200 V
+450 V
A.
(1) only
B.
(1) and (2) only
C.
(1) and (3) only
D.
(2) and (4) only
E.
(1), (2), (3) and (4)
AL-MC-Electrostatics / p.8
30.
(02-IIA-20)
32.
In the above figure the solid lines represent part of
an electric field due to fixed point charge Q (not
shown in the figure). A charge particle q, subjected
(03-IIB-23)
The magnitudes of the charges on two
identical small metal spheres are in the ratio
5:1. The Coulomb interaction force between
them is F1. If they are brought into contact and
then separated to their respective original
positions, the Coulomb interaction force
between them becomes F2. Which of the
following is/are possible magnitude ratios of
F1:F2?
only to electric force in the field, travels along the
(1) 5 : 9
(2) 5 : 4
(3) 5 : 2
dotted curve shown. Which of the following
conclusions can be shown?
A.
q is travelling from X to Y
B.
The charge of q has the same sign as that of
Q
C.
q has a greater speed at X than at Y
D.
The electric potential at X due to Q is
higher than that at Y
31.
(02-IIA-21)
The above figure shows an electrons entering a
uniform field which may be electric or magnetic.
Which of the following description about the
subsequent motion of the electron is correct?
A.
Only in a magnetic field can the electron be
B.
deflected by more than 90
Only in an electric field does the force

depend on the magnitude of the charge on
the electron
C.
Whether the field is electric or magnetic,
the speed of the electron will increase
D.
Whether the field is electric or magnetic,
the magnitude and direction of the force
acting on the electron are constant.
A.
B.
C.
D.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
AL-MC-Electrostatics / p.9
33.
(03-IIB-24)
In the figure, the solid curves are concentric
circles representing set of equipotential
surfaces in an electric field. The dotted curve
ABC represents the path of a charged particle
moving in the field. Which of the following
deductions from the figure is/are correct?
(Neglect the effects of gravity.)
(1)
(2)
(3)
A.
B.
C.
D.
The charged particle is always repelled
from the centre of the concentric
circles.
The speed of the charged particle at A
is equal to that at C.
The kinetic energy of the charged
particle at B is grater than that at A.
(1) only
(3) only
(1) and (2) only
(2) and (3) only