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PHYSICS
1.
2.
3.
GR # 01 (CAPACITOR)
Qqd
(A) zero
(B) 2pÎ l 3
Qqd
Qqd
0
(C) pÎ l 3
(D) 4pÎ l 3
0
0
In the figure initial status of capacitor and their connection is shown. Which of the following is incorrect
about this circuit :
(A) Final charge on each capacitor will be zero
(B) Final total electrical energy of the capacitors will be zero
(C) Total charge flown from A to D is 30µC
(D) Total charge flown from A to D is – 30µC
The circuit was in the shown state for a long time. Now if the switch S is closed
then the net charge that flows through the switch S, will be
4m F
(C)
5.
ENTHUSIAST COURSE
The plates of small size of a parallel plate capacitor are charged as shown. The force on the charged
particle of 'q' at a distance ' l ' from the capacitor is : (Assume that the distance between the plates is
d << l )
(A)
4.
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400
mC
3
(B) 100 mC
100
mC
3
(D) 50 mC
50V
2mF
S
2m F
4mF
In the given circuit, all the capacitors are initially uncharged. After closing the switch S1 for a long time
suddenly S2 is also closed and kept closed for a long time. Total heat produced after closing S2 will be :
(A) 4 Ce2
(B) ½ Ce2
(C) 2 Ce2
(D) 0
A parallel plate capacitor of capacitance C (without dielectrics) is filled by dielectric slabs as shown in
figure. Then the new capacitance of the capacitor is:
(A) 3.9 C
PHYSICS/GR # 01
(B) 4 C
(C) 2.4 C
(D) 3 C
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In the arrangement shown in figure, dielectric constant K1 = 2 and K2 = 3. If the capacitance are C1 and
C1
C2 respectively, then C will be: (The gaps shown are negligible)
2
7.
8.
(A) 1 : 1
(B) 2 : 3
(C) 9 : 5
(D) 25 : 24
A parallel plate capacitor (without dielectric) is charged by a battery and kept connected to the battery.
A dielectric slab of dielectric constant ' k ' is inserted between the plates fully occupying the space
between the plates. The energy density of electric field between the plates will:
(A) increase k2 times (B) decrease k2 times (C) increase k times
(D) decrease k times
In the figure shown the plates of a parallel plate capacitor have unequal charges. Its capacitance is 'C'. P
is a point outside the capacitor and close to the plate of charge –Q. The distance between the plates is 'd'.
(A) A point charge at point 'P' will experience electric force due to capacitor
(B) The potential difference between the plates will be
3Q
2C
(C) The energy stored in the electric field in the region between the plates is
9Q 2
8C
Q2
(D) The force on one plate due to the other plate is 2p Î d2
0
9.
Charged particles with different charge to mass ratios are projected into the region of space between the
plates of a parallel plate capacitor with velocities directed parallel to the plates. All particles have received
their initial kinetic energy by passing the same potential difference V0. The potential difference across the
capacitor plates is V, and the distance between the plates is d. If all the particles are projected from a point
that is exactly in the middle of the distance between the plates and 'l' is the distance travelled (along the
direction of initial velocity) by any particle before hitting any of the plate, then l is dependent as (neglect
the interaction among the particles and effect of induction) :
d
(A) µ V0
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(B) µ
q
m
(C) µ
1
V
(D) µ d
PHYSICS/GR # 01
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10.
JEE (Advanced) 2020
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Two metallic bodies separated by a distance 20 cm, are given equal and opposite charges of magnitude
0.88 mC . The component of electric field along the line AB, between the plates, varies as Ex= 3 x2 + 0.4
N/C, where x (in meters) is the distance from one body towards the other body as shown.
C
x
A
B
20 cm
11.
(A) The capacitance of the system is 10mF
(B) The capacitance of the system is 20mF
(C) The potential difference between A and C is 0.088 Volt.
(D) The potential difference between A and C cannot be determined from the given data.
A circuit has a section AB shown in the figure. The emf of the source equals e = 10V, the capacitor
capacitances are equal to C1 = 1.0 mF and C2 = 2.0 mF, the potential difference fA - fB = 5.0V. The
voltage across each capacitor are
5V
10 V
(A) V1 = 3 , V2 = 3
10 V
5V
,
V
=
2
3
3
5V
A
S
5V
B
C2=3m F
C1
9V
13.
10 V
10 V
,
V
=
2
3
3
(D) V1 = 3 , V2 = 3
In the circuit shown, all the capacitors are initially uncharged. When switch S is closed, a total charge of
12mC passes through point A and a charge of 8mC passes through point B.
(C) V1 =
12.
(B) V1 =
C3
C4=4m F
(A) Value of capacitance of C1 is 2m F
(B) Value of capacitance of C1 is 4m F
(C) Value of capacitance of C3 is 2m F
(D) Value of capacitance of C3 is 6m F
A parallel plate capacitor of capacitance 'C' has charges on its plates initially as shown in the figure.
Now at t = 0, the switch 'S' is closed. Select the correct alternative(s) for this circuit diagram.
S
A B
t=0 -2ec ec
e
(A) In steady state the charges on the outer surfaces of plates 'A' and 'B' will be same in magnitude
and sign.
(B) In steady state the charges on the outer surfaces of plates 'A' and 'B' will be same in magnitude
and opposite in sign.
(C) In steady state the charges on the inner surfaces of the plates 'A' and 'B' will be same in
magnitude and opposite in sign.
(D) The work done by the cell by the time steady state is reached is
PHYSICS/GR # 01
5 e 2C
.
2
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14.
GUIDED REVISION
In the circuit shown in figure if each capacitor is of capacitance 10 µF, find the equivalent capacitance
between points A and B in µF.
P
Q
A
B
S
15.
R
A parallel plate capacitor is to be designed which is to be connected across 1 kV potential difference.
The dielectric material which is to be filled between the plates has dielectric constant K = 6p and
dielectric strength 107 V/m. For safely the electric field is never to exceed 10% of the dielectric strength.
With such specifications, if we want a capacitor of capacitance 50 pF, what minimum area (in mm2 ) of
plates is required for safe working ?
(use e0 =
16.
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ENTHUSIAST COURSE
1
x 10–9 in MKS)
36p
The dielectric constant of the space between the parallel plates of a parallel plate capacitor varies as a
K0
x + K 0 where K0 is a constant and d is the distance
d
between the parallel plates. Surface area of the plates is A. Find it’s capacitance.
function of x according to the relation K =
17.
A dielectric is inserted in a parallel plate capacitor, of capacitance C (without dielectric) and distance
between the plates ' d '. The system is charged by a battery of voltage V. After charging, the capacitor is
hanged from the ceiling, in the vertical plane (as shown in figure), by an insulating massless rod. A
uniform rod of mass ' m ' hinged at O from one end, is connected to the lower plate of the capacitor by
an insulating massless rod from its another end. The rod of mass m is found to be in equilibrium in
horizontal position. Then,
(a) find the dielectric constant K of the dielectric and hence a relation between ' m ', ' d ', C and V for the
above observations to hold good.
(b) if now the dielectric is removed from the capacitor in a very small time interval Dt. Then find the
initial angular acceleration of the rod of mass m.
[Assume the dielectric and the capacitor plates to be massless and the dielectric just touching the
lower plate without exerting any normal force on it.]
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PHYSICS/GR # 01
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18.
A parallel-plate capacitor was lowered into water in a horizontal position, with water filling up the gap
between the plates d =1.0mm wide. Then a constant voltage V = 500 V was applied to the capacitor.
Find the water pressure increment in the gap.
19.
Figure shows two capacitors of capacitance 2mF and 4mF and a cell of 90 V. The switch 'k' is such that
when it is in position 1, the circuit ABCD is closed and when it is in position 2, the circuit BCEF is
closed. The resistance of both the circuits is negligible so that the capacitor gets fully charged instantly
. Initially the switch is in position 1. Then it is turned in position 2. This makes one cycle. It is then again
turned in position 1 and then in position 2. Now two cycles are completed. Find the charge (in mC) on
the capacitor of capacitance 4mF after two cycles.
90 V
D
A
C1=2mF
B
k
C
Position 1
Position 2
C2=4mF
F
E
20.
In the figure shown the capacitor is initially uncharged. Find the current in R3 ( = R) at time ‘t’.
21.
Find the equivalent capacitance between terminals A and B.
22.
Find the capacitance of an infinite circuit formed by the repetition of the same link consisting of two
identical capacitors, each with capacitance C.
23.
Given that CA = 1 m F, CB = 2 m F and CC = 2 m F. Initially each capacitor was charged to potential
differences of VA = 10 v, VB = 40 v and VC = 60 v separately and are kept as shown in figure (a). Now
they are connected as shown in figure (b). The + and - sign shown in figure (b) represent initial polarities.
Find total amount of heat produced in µJ by the time steady state is reached.
PHYSICS/GR # 01
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24.
For the circuit shown in figure, find the potential difference between point P and Q. (Initially capacitors
are uncharged)
25.
In the figure shown, find the e.m.f. e for which charge on 2 mF capacitor is 4 mC.
26.
Find charge on capacitors C, if a battery of e.m.f. E is connected across face diagonal of a cube as shown
in figure. Resistance of each branch (except the branch which contains capacitor) of cube = R.
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PHYSICS/GR # 01