Page 1
JEE Main Previous Year Questions
(2025): Electrostatic Potential and
Capacitance
Q1: A parallel-plate capacitor of capacitance ???? ?? ?? is connected to a 100 V power
supply. Now the intermediate space between the plates is filled with a dielectric
material of dielectric constant ?? = ?? . Due to the introduction of dielectric material,
the extra charge and the change in the electrostatic energy in the capacitor,
respectively, are
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 8 mC and 2.0 J
B. 4 mC and 0.2 J
C. 2 mC and 0.2 J
D. 2 mC and 0.4 J
Ans: B
Solution:
Given, ?? = 2, ?? = 40???? , ?? = 100 ??
??? = ( ???? ) ?? - ???? (As ?? = ???? )
= ( ?? - 1) ????
= ( 2 - 1)× 40 × 10
-6
× 100 = 4 × 10
-3
??
??? = 4????
??? =
1
2
?? '
?? 2
-
1
2
?? ?? 2
=
1
2
?? 2
( ?? '
- ?? ) =
1
2
?? 2
( ???? - ?? )
=
1
2
?? 2
?? ( ?? - 1) =
1
2
× 10
4
× 40 × 10
-6
( 2 - 1)
= ??? = 2 × 10
-1
= 0.2 J
? ??? = 0.2 J
Q2: An electron is made to enter symmetrically between two parallel and equally but
oppositely charged metal plates, each of 10 cm length. The electron emerges out of
the electric field region with a horizontal component of velocity ????
?? ?? /?? . If the
magnitude of the electric field between the plates is ?? . ?? ?? /???? , then the vertical
component of velocity of electron is(mass of electron = ?? . ?? × ????
-????
???? and charge of
electron = ?? . ?? × ????
-????
?? )
Page 2
JEE Main Previous Year Questions
(2025): Electrostatic Potential and
Capacitance
Q1: A parallel-plate capacitor of capacitance ???? ?? ?? is connected to a 100 V power
supply. Now the intermediate space between the plates is filled with a dielectric
material of dielectric constant ?? = ?? . Due to the introduction of dielectric material,
the extra charge and the change in the electrostatic energy in the capacitor,
respectively, are
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 8 mC and 2.0 J
B. 4 mC and 0.2 J
C. 2 mC and 0.2 J
D. 2 mC and 0.4 J
Ans: B
Solution:
Given, ?? = 2, ?? = 40???? , ?? = 100 ??
??? = ( ???? ) ?? - ???? (As ?? = ???? )
= ( ?? - 1) ????
= ( 2 - 1)× 40 × 10
-6
× 100 = 4 × 10
-3
??
??? = 4????
??? =
1
2
?? '
?? 2
-
1
2
?? ?? 2
=
1
2
?? 2
( ?? '
- ?? ) =
1
2
?? 2
( ???? - ?? )
=
1
2
?? 2
?? ( ?? - 1) =
1
2
× 10
4
× 40 × 10
-6
( 2 - 1)
= ??? = 2 × 10
-1
= 0.2 J
? ??? = 0.2 J
Q2: An electron is made to enter symmetrically between two parallel and equally but
oppositely charged metal plates, each of 10 cm length. The electron emerges out of
the electric field region with a horizontal component of velocity ????
?? ?? /?? . If the
magnitude of the electric field between the plates is ?? . ?? ?? /???? , then the vertical
component of velocity of electron is(mass of electron = ?? . ?? × ????
-????
???? and charge of
electron = ?? . ?? × ????
-????
?? )
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 1 × 10
6
m/s
B. 16 × 10
6
m/s
C. 16 × 10
4
m/s
D. 0
Ans: B
Solution:
No force in horizontal direction, i.e., ?? ?? = 0
? ?? ?? = 0
So, ?? ?? = constant
hence, ?? =
?? ?? ?? …. (1)
Now, for y -direction, using Ist equation of motion,
?? ?? = ?? ?? + ?? ?? ??
? ?? ?? = 0 +
????
?? (
?? ?? ?? ) (from (1) and usiung ?? = ???? and ?? =
?? ?? )
? ?? ?? =
1.6 × 10
-19
× 9.1 × 10
2
× 0.1
9.1 × 10
-31
× 10
6
= 1.6 × 10
7
m/s
? ?? ?? = 16 × 10
6
m/s.
Q3: Which one of the following is the correct dimensional formula for the capacitance
in F ? M, L, T and ?? stand for unit of mass, length, time and charge,
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. [F] = [CM
-1
L
-2
T
2
]
B. [?? ] = [?? 2
?? -2
?? 2
?? 2
]
C. [F] = [C
2
M
-1
L
-2
T
2
]
D. [F] = [CM
-2
L
-2
T
-2
]
Ans: C
Solution:
Page 3
JEE Main Previous Year Questions
(2025): Electrostatic Potential and
Capacitance
Q1: A parallel-plate capacitor of capacitance ???? ?? ?? is connected to a 100 V power
supply. Now the intermediate space between the plates is filled with a dielectric
material of dielectric constant ?? = ?? . Due to the introduction of dielectric material,
the extra charge and the change in the electrostatic energy in the capacitor,
respectively, are
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 8 mC and 2.0 J
B. 4 mC and 0.2 J
C. 2 mC and 0.2 J
D. 2 mC and 0.4 J
Ans: B
Solution:
Given, ?? = 2, ?? = 40???? , ?? = 100 ??
??? = ( ???? ) ?? - ???? (As ?? = ???? )
= ( ?? - 1) ????
= ( 2 - 1)× 40 × 10
-6
× 100 = 4 × 10
-3
??
??? = 4????
??? =
1
2
?? '
?? 2
-
1
2
?? ?? 2
=
1
2
?? 2
( ?? '
- ?? ) =
1
2
?? 2
( ???? - ?? )
=
1
2
?? 2
?? ( ?? - 1) =
1
2
× 10
4
× 40 × 10
-6
( 2 - 1)
= ??? = 2 × 10
-1
= 0.2 J
? ??? = 0.2 J
Q2: An electron is made to enter symmetrically between two parallel and equally but
oppositely charged metal plates, each of 10 cm length. The electron emerges out of
the electric field region with a horizontal component of velocity ????
?? ?? /?? . If the
magnitude of the electric field between the plates is ?? . ?? ?? /???? , then the vertical
component of velocity of electron is(mass of electron = ?? . ?? × ????
-????
???? and charge of
electron = ?? . ?? × ????
-????
?? )
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 1 × 10
6
m/s
B. 16 × 10
6
m/s
C. 16 × 10
4
m/s
D. 0
Ans: B
Solution:
No force in horizontal direction, i.e., ?? ?? = 0
? ?? ?? = 0
So, ?? ?? = constant
hence, ?? =
?? ?? ?? …. (1)
Now, for y -direction, using Ist equation of motion,
?? ?? = ?? ?? + ?? ?? ??
? ?? ?? = 0 +
????
?? (
?? ?? ?? ) (from (1) and usiung ?? = ???? and ?? =
?? ?? )
? ?? ?? =
1.6 × 10
-19
× 9.1 × 10
2
× 0.1
9.1 × 10
-31
× 10
6
= 1.6 × 10
7
m/s
? ?? ?? = 16 × 10
6
m/s.
Q3: Which one of the following is the correct dimensional formula for the capacitance
in F ? M, L, T and ?? stand for unit of mass, length, time and charge,
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. [F] = [CM
-1
L
-2
T
2
]
B. [?? ] = [?? 2
?? -2
?? 2
?? 2
]
C. [F] = [C
2
M
-1
L
-2
T
2
]
D. [F] = [CM
-2
L
-2
T
-2
]
Ans: C
Solution:
The capacitance (in farads) is defined as the ratio of charge to potential difference. Let's go
through the steps:
Capacitance is given by:
?? =
?? ??
where:
?? is the charge with dimensional symbol ?? .
?? is the potential difference.
Voltage (potential difference) is defined as energy per unit charge:
?? =
?? ??
where:
?? is energy with dimensions:
[?? ] = [?? ?? 2
?? -2
]
Therefore, the dimensions of voltage are:
[?? ] =
[?? ?? 2
?? -2
]
[?? ]
Now, substitute this back into the expression for capacitance:
[?? ] =
[?? ]
[?? ?? 2
?? -2
]/[?? ]
=
[?? ]
2
?? ?? 2
?? -2
Simplifying gives:
[?? ] = [?? 2
?? -1
?? -2
?? 2
]
Comparing with the given options, we see that Option C is:
[?? ] = [?? 2
?? -1
?? -2
?? 2
]
Thus, the correct dimensional formula for the capacitance in farads is given by Option C.
Q4: Identify the valid statements relevant to the given circuit at the instant when the
key is closed.
Page 4
JEE Main Previous Year Questions
(2025): Electrostatic Potential and
Capacitance
Q1: A parallel-plate capacitor of capacitance ???? ?? ?? is connected to a 100 V power
supply. Now the intermediate space between the plates is filled with a dielectric
material of dielectric constant ?? = ?? . Due to the introduction of dielectric material,
the extra charge and the change in the electrostatic energy in the capacitor,
respectively, are
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 8 mC and 2.0 J
B. 4 mC and 0.2 J
C. 2 mC and 0.2 J
D. 2 mC and 0.4 J
Ans: B
Solution:
Given, ?? = 2, ?? = 40???? , ?? = 100 ??
??? = ( ???? ) ?? - ???? (As ?? = ???? )
= ( ?? - 1) ????
= ( 2 - 1)× 40 × 10
-6
× 100 = 4 × 10
-3
??
??? = 4????
??? =
1
2
?? '
?? 2
-
1
2
?? ?? 2
=
1
2
?? 2
( ?? '
- ?? ) =
1
2
?? 2
( ???? - ?? )
=
1
2
?? 2
?? ( ?? - 1) =
1
2
× 10
4
× 40 × 10
-6
( 2 - 1)
= ??? = 2 × 10
-1
= 0.2 J
? ??? = 0.2 J
Q2: An electron is made to enter symmetrically between two parallel and equally but
oppositely charged metal plates, each of 10 cm length. The electron emerges out of
the electric field region with a horizontal component of velocity ????
?? ?? /?? . If the
magnitude of the electric field between the plates is ?? . ?? ?? /???? , then the vertical
component of velocity of electron is(mass of electron = ?? . ?? × ????
-????
???? and charge of
electron = ?? . ?? × ????
-????
?? )
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 1 × 10
6
m/s
B. 16 × 10
6
m/s
C. 16 × 10
4
m/s
D. 0
Ans: B
Solution:
No force in horizontal direction, i.e., ?? ?? = 0
? ?? ?? = 0
So, ?? ?? = constant
hence, ?? =
?? ?? ?? …. (1)
Now, for y -direction, using Ist equation of motion,
?? ?? = ?? ?? + ?? ?? ??
? ?? ?? = 0 +
????
?? (
?? ?? ?? ) (from (1) and usiung ?? = ???? and ?? =
?? ?? )
? ?? ?? =
1.6 × 10
-19
× 9.1 × 10
2
× 0.1
9.1 × 10
-31
× 10
6
= 1.6 × 10
7
m/s
? ?? ?? = 16 × 10
6
m/s.
Q3: Which one of the following is the correct dimensional formula for the capacitance
in F ? M, L, T and ?? stand for unit of mass, length, time and charge,
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. [F] = [CM
-1
L
-2
T
2
]
B. [?? ] = [?? 2
?? -2
?? 2
?? 2
]
C. [F] = [C
2
M
-1
L
-2
T
2
]
D. [F] = [CM
-2
L
-2
T
-2
]
Ans: C
Solution:
The capacitance (in farads) is defined as the ratio of charge to potential difference. Let's go
through the steps:
Capacitance is given by:
?? =
?? ??
where:
?? is the charge with dimensional symbol ?? .
?? is the potential difference.
Voltage (potential difference) is defined as energy per unit charge:
?? =
?? ??
where:
?? is energy with dimensions:
[?? ] = [?? ?? 2
?? -2
]
Therefore, the dimensions of voltage are:
[?? ] =
[?? ?? 2
?? -2
]
[?? ]
Now, substitute this back into the expression for capacitance:
[?? ] =
[?? ]
[?? ?? 2
?? -2
]/[?? ]
=
[?? ]
2
?? ?? 2
?? -2
Simplifying gives:
[?? ] = [?? 2
?? -1
?? -2
?? 2
]
Comparing with the given options, we see that Option C is:
[?? ] = [?? 2
?? -1
?? -2
?? 2
]
Thus, the correct dimensional formula for the capacitance in farads is given by Option C.
Q4: Identify the valid statements relevant to the given circuit at the instant when the
key is closed.
A. There will be no current through resistor ?? .
B. There will be maximum current in the connecting wires.
C. Potential difference between the capacitor plates A and B is minimum.
D. Charge on the capacitor plates is minimum.
Choose the correct answer from the options given below:
JEE Main 2025 (Online) 23rd January Morning Shift
Options:
A. A, C Only
B. C, D Only
C. A, B, D Only
D. B, C, D Only
Ans: D
Solution:
Initially, when the key in the circuit is closed, the capacitor behaves like a short circuit. This
means:
Maximum Current: The current flowing through the circuit will be at its maximum since there is
effectively no resistance offered by the capacitor, as it behaves like a wire.
Current Through R: Since the current is flowing through the circuit, including any resistors in
series, the statement that there is no current through resistor ?? is incorrect.
Charge on the Capacitor: The charge stored on the capacitor plates is initially zero because it
behaves as a short circuit.
Potential Difference: The potential difference across the capacitor is also zero at this instant
because it is fully discharged.
Therefore, the valid statements at this instant are that the current in the circuit is at a
maximum, the charge on the capacitor is zero, and the potential difference across the capacitor
is zero.
Q5: A parallel plate capacitor was made with two rectangular plates, each with a
length of ?? = ?? ???? and breath of ?? = ?? ???? . The distance between the plates is ?? ?? ?? .
Out of the following, which are the ways to increase the capacitance by a factor of 10
?
Page 5
JEE Main Previous Year Questions
(2025): Electrostatic Potential and
Capacitance
Q1: A parallel-plate capacitor of capacitance ???? ?? ?? is connected to a 100 V power
supply. Now the intermediate space between the plates is filled with a dielectric
material of dielectric constant ?? = ?? . Due to the introduction of dielectric material,
the extra charge and the change in the electrostatic energy in the capacitor,
respectively, are
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 8 mC and 2.0 J
B. 4 mC and 0.2 J
C. 2 mC and 0.2 J
D. 2 mC and 0.4 J
Ans: B
Solution:
Given, ?? = 2, ?? = 40???? , ?? = 100 ??
??? = ( ???? ) ?? - ???? (As ?? = ???? )
= ( ?? - 1) ????
= ( 2 - 1)× 40 × 10
-6
× 100 = 4 × 10
-3
??
??? = 4????
??? =
1
2
?? '
?? 2
-
1
2
?? ?? 2
=
1
2
?? 2
( ?? '
- ?? ) =
1
2
?? 2
( ???? - ?? )
=
1
2
?? 2
?? ( ?? - 1) =
1
2
× 10
4
× 40 × 10
-6
( 2 - 1)
= ??? = 2 × 10
-1
= 0.2 J
? ??? = 0.2 J
Q2: An electron is made to enter symmetrically between two parallel and equally but
oppositely charged metal plates, each of 10 cm length. The electron emerges out of
the electric field region with a horizontal component of velocity ????
?? ?? /?? . If the
magnitude of the electric field between the plates is ?? . ?? ?? /???? , then the vertical
component of velocity of electron is(mass of electron = ?? . ?? × ????
-????
???? and charge of
electron = ?? . ?? × ????
-????
?? )
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 1 × 10
6
m/s
B. 16 × 10
6
m/s
C. 16 × 10
4
m/s
D. 0
Ans: B
Solution:
No force in horizontal direction, i.e., ?? ?? = 0
? ?? ?? = 0
So, ?? ?? = constant
hence, ?? =
?? ?? ?? …. (1)
Now, for y -direction, using Ist equation of motion,
?? ?? = ?? ?? + ?? ?? ??
? ?? ?? = 0 +
????
?? (
?? ?? ?? ) (from (1) and usiung ?? = ???? and ?? =
?? ?? )
? ?? ?? =
1.6 × 10
-19
× 9.1 × 10
2
× 0.1
9.1 × 10
-31
× 10
6
= 1.6 × 10
7
m/s
? ?? ?? = 16 × 10
6
m/s.
Q3: Which one of the following is the correct dimensional formula for the capacitance
in F ? M, L, T and ?? stand for unit of mass, length, time and charge,
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. [F] = [CM
-1
L
-2
T
2
]
B. [?? ] = [?? 2
?? -2
?? 2
?? 2
]
C. [F] = [C
2
M
-1
L
-2
T
2
]
D. [F] = [CM
-2
L
-2
T
-2
]
Ans: C
Solution:
The capacitance (in farads) is defined as the ratio of charge to potential difference. Let's go
through the steps:
Capacitance is given by:
?? =
?? ??
where:
?? is the charge with dimensional symbol ?? .
?? is the potential difference.
Voltage (potential difference) is defined as energy per unit charge:
?? =
?? ??
where:
?? is energy with dimensions:
[?? ] = [?? ?? 2
?? -2
]
Therefore, the dimensions of voltage are:
[?? ] =
[?? ?? 2
?? -2
]
[?? ]
Now, substitute this back into the expression for capacitance:
[?? ] =
[?? ]
[?? ?? 2
?? -2
]/[?? ]
=
[?? ]
2
?? ?? 2
?? -2
Simplifying gives:
[?? ] = [?? 2
?? -1
?? -2
?? 2
]
Comparing with the given options, we see that Option C is:
[?? ] = [?? 2
?? -1
?? -2
?? 2
]
Thus, the correct dimensional formula for the capacitance in farads is given by Option C.
Q4: Identify the valid statements relevant to the given circuit at the instant when the
key is closed.
A. There will be no current through resistor ?? .
B. There will be maximum current in the connecting wires.
C. Potential difference between the capacitor plates A and B is minimum.
D. Charge on the capacitor plates is minimum.
Choose the correct answer from the options given below:
JEE Main 2025 (Online) 23rd January Morning Shift
Options:
A. A, C Only
B. C, D Only
C. A, B, D Only
D. B, C, D Only
Ans: D
Solution:
Initially, when the key in the circuit is closed, the capacitor behaves like a short circuit. This
means:
Maximum Current: The current flowing through the circuit will be at its maximum since there is
effectively no resistance offered by the capacitor, as it behaves like a wire.
Current Through R: Since the current is flowing through the circuit, including any resistors in
series, the statement that there is no current through resistor ?? is incorrect.
Charge on the Capacitor: The charge stored on the capacitor plates is initially zero because it
behaves as a short circuit.
Potential Difference: The potential difference across the capacitor is also zero at this instant
because it is fully discharged.
Therefore, the valid statements at this instant are that the current in the circuit is at a
maximum, the charge on the capacitor is zero, and the potential difference across the capacitor
is zero.
Q5: A parallel plate capacitor was made with two rectangular plates, each with a
length of ?? = ?? ???? and breath of ?? = ?? ???? . The distance between the plates is ?? ?? ?? .
Out of the following, which are the ways to increase the capacitance by a factor of 10
?
A. ?? = ???? ???? , ?? = ?? ???? , ?? = ?? ?? ??
B. ?? = ?? ???? , ?? = ?? ???? , ?? = ???? ?? ??
C. ?? = ?? ???? , ?? = ?? ???? , ?? = ?? ?? ??
D. ?? = ?? ???? , ?? = ?? ???? , ?? = ???? ?? ??
E. ?? = ?? ???? , ?? = ?? ???? , ?? = ?? ?? ??
Choose the correct answer from the options given below:
JEE Main 2025 (Online) 24th January Morning Shift
Options:
A. C only
B. A only
C. B and D only
D. C and E only
Ans: D
Solution:
The capacitance of a parallel plate capacitor is given by
?? =
?? 0
?? ?? ,
where:
?? 0
is the permittivity of free space,
?? is the area of a plate, and
?? is the separation between the plates.
A change in the capacitor's dimensions will change its capacitance by a factor of
?? new
?? initial
=
?? new
?? initial
·
?? initial
?? new
.
The initial dimensions are:
Length: ?? = 3 cm = 0.03 m,
Breadth: ?? = 1 cm = 0.01 m,
Hence, the original area is
?? initial
= 0.03 × 0.01 = 3 × 10
-4
m
2
,
Plate separation: ?? initial
= 3?? m = 3 × 10
-6
m.
For each modification, we compare the new factor:
Case C:
New dimensions:
?? = 6 cm = 0.06 m, ?? = 5 cm = 0.05 m.
New area:
?? new
= 0.06 × 0.05 = 3 × 10
-3
m
2
.
Ratio of areas:
?? new
?? initial
=
3×10
-3
3×10
-4
= 10.
The plate separation is unchanged:
?? initial
?? new
=
3×10
-6
3×10
-6
= 1.
Overall factor:
10 × 1 = 10.
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