1
LAKSHYA JEE (2024)
Electrostatic Potential and Capacitance
1.
2.
The potential energy of a particle in a force field is:
A B
U = 2 − , where A and B are positive constants
r
r
and r is the distance of particle from the centre of the
field. For stable equilibrium the distance of the
particle is:
(1) B/A
(2) B/2A
(3) 2A/B
(4) A/B
Two charges of equal magnitude q are placed in air at
a distance 2a apart and third charge –2q is placed at
mid-point. The potential energy of the system is: (0
= permittivity of free space)
(1) −
–q
x
6.
q2
8 0 a
(2) 5.5
(3) 4
(4) 1.5
Four equal point charge Q each are placed in the
xy-plane at (0, 2), (4, 2), (4, -2) and (0, -2). The work
required to put a fifth charge Q at the origin of the
coordinate system will be
5q 2
(3) −
8 0 a
(2)
Q2 
1 
1+


4 0 
5
Two equal point charges q are fixed at x = –a and
x = +a on x-axis. Another point charge Q is placed at
the origin. The change in electrical potential energy
of Q, when it is displaced by a small amount x along
x-axis, is approximately proportional to:
(1) x
(2) x2
1
(3) x3
(4)
x
In bringing an electron towards proton, the
electrostatic potential energy of the system:
(1) decreases
(2) increases
(3) remains same
(4) becomes zero
x
(1) 2
Q2 
1 
1+ 

4 0 
3
7q 2
8 0 a
–q
+Q
(1)
(4) −
4.
Three charges –q, +Q and –q are placed in a straight
line as shown. If the total potential energy of the
q
system is zero, then the ratio
is:
Q
3q 2
8 0 a
(2) −
3.
5.
DPP-02
Q2
(3)
4 0
(4)
7.
Q2
2 2 0
Four point charges – Q, – q, 2q and 2Q are placed,
one at each corner of the square. The relation between
Q and q for which the potential at the centre of the
square is zero is
(1) Q = – q
(2) Q = –
(3) Q = q
(4) Q =
1
q
1
q
2
8.
Three identical charges are placed at corners of an
equilateral triangle of side l. If force between any two
charges is F, the work required to double the
dimensions of triangle is
(1) – 3 Fl
(3) (–3/2) Fl
9.
(2) 3 Fl
(4) (3/2) Fl
10.
Six unit points charges are kept at the vertices of a
regular hexagon of side L and centre O, as shown in
1
, which of the
the figure. Given that K =
4 0 L2
following statement is wrong?
Charges + q and – q are placed at points A and B
respectively which are a distance 2L apart, C is the
mid-point between A and B, The work done in
moving a charge + Q along the semicircle CRD is
(1)
(3)
qQ
4 0 L
qQ
6 0 L
(2) −
(4) −
qQ
4 0 L
qQ
6 0 L
(1)
(2)
(3)
(4)
The electric field at O is 6 K along OD
The potential at O is zero
The potential at all points on the line PR is same
The potential at all points on the line ST is same
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Note: Kindly find the Video Solution of DPPs Questions in the DPPs Section.
Answer Key
1.
(3)
6.
(2)
2.
(4)
7.
(1)
3.
(2)
8.
(3)
4.
(1)
9.
(4)
5.
(3)
10.
(4)
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