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SINGLE CORRECT
Q.1 Two identical conducting spheres, having charges of opposite sign, attract each other with a force of
0.108 N when separated by 0.5 m. The spheres are connected by a conducting wire, which is then
removed, and thereafter, they repel each other with a force of 0.036 N. The initial charges on the
spheres are
(A) 5 10-6 C and 15 10-6 C (B) 1.0 10-6 C and 3.0 10-6 C
(C) 2.0 10-6
C and 6.0 10-6
C (D) 0.5 10-6
C and 1.5 10-6
C
Q.2 A point charge 50C is located in the XY plane at the point of position vector r i j0
2 3 . What is the
electric field at the point of position vectorr i j 8 5
(A) 1200V/m (B) 0.04V/m (C) 900V/m (D) 4500 V/m
Q.3 A point charge q is placed at origin. LetAE
,
BE
andCE
be the electric field at three points
A (1, 2, 3), B (1, 1, 1) and C (2, 2, 2) due to charge q. Then
[i]AE
BE
[ii] |BE
| = 4 |
CE
|
select the correct alternative
(A) only [i] is correct (B) only [ii] is correct(C) both [i] and [ii] are correct (D) both [i] and [ii] are wrong
Q.4 Two identical point charges are placed at a separation ofl. P is a point on the line joining the charges, at
a distance x from any one charge. The field at P is E. E is plotted against x for values of x from close to
zero to slightly less than l. Which of the following best represents the resulting curve?
(A) (B) (C) (D)
Q.5 A particle of mass m and charge Q is placed in an electric field E which varies with time t ass
E = E0sint. It will undergo simple harmonic motion of amplitude
(A)2
20
m
QE
(B) 2
0
m
QE
(C) 2
0
m
QE
(D)
m
QE0
Q.6 Four charges are arranged at the corners of a square ABCD, as shown. The
force on a +ve charge kept at the centre of the square is
(A) zero (B) along diagonal AC
(C) along diagonal BD (D) perpendicular to the side AB
Q.7 Two free positive charges 4q and q are a distance l apart. What charge Q is needed to achieve equilibrium
for the entire system and where should it be placed form charge q?
(A) Q =9
4q (negative) at
3
l(B) Q =
9
4q (positive) at
3
l
(C) Q = q (positive) at3
l(D) Q = q (negative) at
3
l
Q.8 Six charges are placed at the corner of a regular hexagon as shown. If an electron
is placed at its centre O, force on it will be:
(A) Zero (B) Along OF
(C) Along OC (D) None of these
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Q.9 Two identical positive charges are fixed on the y-axis, at equal distances from the origin O. A particle
with a negative charge starts on the x-axis at a large distance from O, moves along the + x-axis, passes
through O and moves far away from O. Its acceleration a is taken as positive along its direction of
motion. The particles acceleration a is plotted against its x-coordinate. Which of the following best
represents the plot?
(A) (B) (C) (D)
Q.10 Four equal positive charges are fixed at the vertices of a square of side L. Z-axis is perpendicular to the
plane of the square. The point z = 0 is the point where the diagonals of the square intersect each other.
The plot of electric field due to the four charges, as one moves on the z-axis.
(A) (B) (C) (D)
Q.11 A nonconducting ring of radius R has uniformly distributed positive charge Q. A small part of the ring, of
length d, is removed (d
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Q.16 A small particle of mass m and charge q is placed at point P and released. If R >> x, the particle will
undergo oscillations along the axis of symmetry with an angular frequency that is equal to
(A) 30mR4
qQ
(B) 40mR4
qQx
(C) 30mR4
qQ
(D) 40mR4
qQx
Q.17 Which of the following is a volt :(A) Erg per cm (B) Joule per coulomb
(C) Erg per ampere (D) Newton / (coulomb x m2)
Q.18 n small drops of same size are charged to V volts each. If they coalesce to form a signal large drop, then
its potential will be
(A) V/n (B) Vn (C) Vn1/3 (D) Vn2/3
Q.19 1000 identical drops of mercury are charged to a potential of 1 V each. They join to form a single drop.
The potential of this drop will be
(A) 0.01 V (B) 0.1 V (C) 10 V (D) 100 V
Q.20 Potential difference between centre & the surface of sphere of radius R and uniform volumecharge densitywithin it will be :(A)
R2
06(B)
R2
04(C) 0 (D)
R2
02
Q.21 If the electric potential of the inner metal sphere is 10 volt & that of the
outer shell is 5 volt, then the potential at the centre will be :
(A) 10 volt (B) 5 volt (C) 15 volt (D) 0
Q.22 Three concentric metallic spherical shell A, B and C or radii a, b and c (a < b < c) have surface charge
densities , + , and respectively. The potential of shell A is :
(A) 0 [a + b c] (B) 0 [a b + c] (C) 0 [b a c] (D) none
Q.23 A charged particle having some mass is resting in equilibrium at a height H above the centre of a uniformly
charged non-conducting horizontal ring of radius R. The force of gravity acts downwards. The equilibrium
of the particle will be stable
(A) for all values of H (B) only if H >2
R(C) only if H