Page 1
JEE Main Previous Year Questions
(2025): Dual Nature of Matter and
Radiation
Q1: An electron in the ground state of the hydrogen atom has the orbital radius of
?? .?? × ????
-????
?? while that for the electron in third excited state is ?? .???? × ????
-????
?? .
The ratio of the de Broglie wavelengths of electron in the ground state to that in the
excited state is
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 4
B. 3
C. 9
D. 16
Ans: A
Solution:
We know, ?? =
h
????
and ?????? =
?? h
2??
? ???? =
?? h
2????
So, ?? =
h
?? h
2???? = 2?? ?? ??
? ?? ?
?? ??
We can write,
?? ?? ?? ?? = (
?? ?? ?? ?? )(
?? ?? ?? ?? )
?
?? ?? ?? ?? = (
5.3× 10
-11
84.8× 10
-11
)(
4
1
) =
1
4
?
?? ?? ?? ?? = 4
Q2: The work functions of cesium ( Cs ) and lithium ( Li ) metals are 1.9 eV and 2.5 eV ,
respectively. If we incident a light of wavelength 550 nm on these two metal surfaces,
then photo-electric effect is possible for the case of
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. Both Cs and Li
B. Neither Cs nor Li
C. Li only
D. Cs only
Page 2
JEE Main Previous Year Questions
(2025): Dual Nature of Matter and
Radiation
Q1: An electron in the ground state of the hydrogen atom has the orbital radius of
?? .?? × ????
-????
?? while that for the electron in third excited state is ?? .???? × ????
-????
?? .
The ratio of the de Broglie wavelengths of electron in the ground state to that in the
excited state is
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 4
B. 3
C. 9
D. 16
Ans: A
Solution:
We know, ?? =
h
????
and ?????? =
?? h
2??
? ???? =
?? h
2????
So, ?? =
h
?? h
2???? = 2?? ?? ??
? ?? ?
?? ??
We can write,
?? ?? ?? ?? = (
?? ?? ?? ?? )(
?? ?? ?? ?? )
?
?? ?? ?? ?? = (
5.3× 10
-11
84.8× 10
-11
)(
4
1
) =
1
4
?
?? ?? ?? ?? = 4
Q2: The work functions of cesium ( Cs ) and lithium ( Li ) metals are 1.9 eV and 2.5 eV ,
respectively. If we incident a light of wavelength 550 nm on these two metal surfaces,
then photo-electric effect is possible for the case of
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. Both Cs and Li
B. Neither Cs nor Li
C. Li only
D. Cs only
Ans: D
Solution:
For photo-electric effect, energy of the photon must be greater than the work function of the
metal.
We know, ?? =
1240
?? =
1240
550
(as ?? = 550 nm given)
? ?? = 2.25eV
here, ?? > ?? ????
So, ?? ?? only.
Q3: A light source of wavelength ?? illuminates a metal surface and electrons are
ejected with maximum kinetic energy of 2 eV . If the same surface is illuminated by a
light source of wavelength
?? ?? , then the maximum kinetic energy of ejected electrons
will be (The work function of metal is ?? ???? )
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. 5 eV
B. 3 eV
C. 2 eV
D. 6 eV
Ans: A
Solution:
Let's break down the problem step by step.
The photoelectric equation is given by:
?? max
=
h?? ?? - ??
where:
?? max
is the maximum kinetic energy of the electrons.
h?? ?? is the energy of the incident photon.
?? is the work function of the metal.
For the initial light source of wavelength ?? , we know:
2eV=
h?? ?? - 1eV
Solving for
h?? ?? gives:
h?? ?? = 2eV+ 1eV= 3eV
Now, if the wavelength is halved to
?? 2
, the photon energy becomes:
h?? ?? /2
=
2h?? ?? = 2× 3eV= 6eV
The maximum kinetic energy for the new wavelength is then:
Page 3
JEE Main Previous Year Questions
(2025): Dual Nature of Matter and
Radiation
Q1: An electron in the ground state of the hydrogen atom has the orbital radius of
?? .?? × ????
-????
?? while that for the electron in third excited state is ?? .???? × ????
-????
?? .
The ratio of the de Broglie wavelengths of electron in the ground state to that in the
excited state is
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 4
B. 3
C. 9
D. 16
Ans: A
Solution:
We know, ?? =
h
????
and ?????? =
?? h
2??
? ???? =
?? h
2????
So, ?? =
h
?? h
2???? = 2?? ?? ??
? ?? ?
?? ??
We can write,
?? ?? ?? ?? = (
?? ?? ?? ?? )(
?? ?? ?? ?? )
?
?? ?? ?? ?? = (
5.3× 10
-11
84.8× 10
-11
)(
4
1
) =
1
4
?
?? ?? ?? ?? = 4
Q2: The work functions of cesium ( Cs ) and lithium ( Li ) metals are 1.9 eV and 2.5 eV ,
respectively. If we incident a light of wavelength 550 nm on these two metal surfaces,
then photo-electric effect is possible for the case of
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. Both Cs and Li
B. Neither Cs nor Li
C. Li only
D. Cs only
Ans: D
Solution:
For photo-electric effect, energy of the photon must be greater than the work function of the
metal.
We know, ?? =
1240
?? =
1240
550
(as ?? = 550 nm given)
? ?? = 2.25eV
here, ?? > ?? ????
So, ?? ?? only.
Q3: A light source of wavelength ?? illuminates a metal surface and electrons are
ejected with maximum kinetic energy of 2 eV . If the same surface is illuminated by a
light source of wavelength
?? ?? , then the maximum kinetic energy of ejected electrons
will be (The work function of metal is ?? ???? )
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. 5 eV
B. 3 eV
C. 2 eV
D. 6 eV
Ans: A
Solution:
Let's break down the problem step by step.
The photoelectric equation is given by:
?? max
=
h?? ?? - ??
where:
?? max
is the maximum kinetic energy of the electrons.
h?? ?? is the energy of the incident photon.
?? is the work function of the metal.
For the initial light source of wavelength ?? , we know:
2eV=
h?? ?? - 1eV
Solving for
h?? ?? gives:
h?? ?? = 2eV+ 1eV= 3eV
Now, if the wavelength is halved to
?? 2
, the photon energy becomes:
h?? ?? /2
=
2h?? ?? = 2× 3eV= 6eV
The maximum kinetic energy for the new wavelength is then:
?? max
'
= 6eV- 1eV= 5eV
Therefore, the maximum kinetic energy of the ejected electrons when the surface is illuminated
by a light source of wavelength
?? 2
is 5 eV .
The correct answer is Option A.
Q4: A sub-atomic particle of mass ????
-????
???? is moving with a velocity ?? .???? ×
????
?? ?? /?? . Under the matter wave consideration, the particle will behave closely like
(?? = ?? .???? × ????
-????
?? .?? )
JEE Main 2025 (Online) 23rd January Morning Shift
Options:
A. X-rays
B. Infra-red radiation
C. Gamma rays
D. Visible radiation
Ans: A
Solution:
To find the matter wave behavior of the particle, we use the de Broglie wavelength formula:
?? =
h
????
where:
h= 6.63× 10
-34
J · s is Planck's constant,
?? = 10
-30
kg is the mass of the particle, and
?? = 2.21× 10
6
m/s is its velocity.
Follow these steps:
Substitute the values into the formula:
?? =
6.63× 10
-34
(10
-30
)(2.21× 10
6
)
Calculate the denominator:
10
-30
× 2.21× 10
6
= 2.21× 10
-24
Now compute the wavelength:
?? ˜
6.63× 10
-34
2.21× 10
-24
˜ 3 × 10
-10
m
This wavelength, roughly 3 × 10
-10
m (or 0.3 nm ), lies within the X-ray portion of the
electromagnetic spectrum, since X-rays typically have wavelengths in the range of about 0.01
nm to 10 nm .
Therefore, under the matter wave consideration, the particle will behave closely like:
Option A: X-rays.
Q5: In photoelectric effect an em-wave is incident on a metal surface and electrons
are ejected from the surface. If the work function of the metal is 2.14 eV and stopping
Page 4
JEE Main Previous Year Questions
(2025): Dual Nature of Matter and
Radiation
Q1: An electron in the ground state of the hydrogen atom has the orbital radius of
?? .?? × ????
-????
?? while that for the electron in third excited state is ?? .???? × ????
-????
?? .
The ratio of the de Broglie wavelengths of electron in the ground state to that in the
excited state is
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 4
B. 3
C. 9
D. 16
Ans: A
Solution:
We know, ?? =
h
????
and ?????? =
?? h
2??
? ???? =
?? h
2????
So, ?? =
h
?? h
2???? = 2?? ?? ??
? ?? ?
?? ??
We can write,
?? ?? ?? ?? = (
?? ?? ?? ?? )(
?? ?? ?? ?? )
?
?? ?? ?? ?? = (
5.3× 10
-11
84.8× 10
-11
)(
4
1
) =
1
4
?
?? ?? ?? ?? = 4
Q2: The work functions of cesium ( Cs ) and lithium ( Li ) metals are 1.9 eV and 2.5 eV ,
respectively. If we incident a light of wavelength 550 nm on these two metal surfaces,
then photo-electric effect is possible for the case of
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. Both Cs and Li
B. Neither Cs nor Li
C. Li only
D. Cs only
Ans: D
Solution:
For photo-electric effect, energy of the photon must be greater than the work function of the
metal.
We know, ?? =
1240
?? =
1240
550
(as ?? = 550 nm given)
? ?? = 2.25eV
here, ?? > ?? ????
So, ?? ?? only.
Q3: A light source of wavelength ?? illuminates a metal surface and electrons are
ejected with maximum kinetic energy of 2 eV . If the same surface is illuminated by a
light source of wavelength
?? ?? , then the maximum kinetic energy of ejected electrons
will be (The work function of metal is ?? ???? )
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. 5 eV
B. 3 eV
C. 2 eV
D. 6 eV
Ans: A
Solution:
Let's break down the problem step by step.
The photoelectric equation is given by:
?? max
=
h?? ?? - ??
where:
?? max
is the maximum kinetic energy of the electrons.
h?? ?? is the energy of the incident photon.
?? is the work function of the metal.
For the initial light source of wavelength ?? , we know:
2eV=
h?? ?? - 1eV
Solving for
h?? ?? gives:
h?? ?? = 2eV+ 1eV= 3eV
Now, if the wavelength is halved to
?? 2
, the photon energy becomes:
h?? ?? /2
=
2h?? ?? = 2× 3eV= 6eV
The maximum kinetic energy for the new wavelength is then:
?? max
'
= 6eV- 1eV= 5eV
Therefore, the maximum kinetic energy of the ejected electrons when the surface is illuminated
by a light source of wavelength
?? 2
is 5 eV .
The correct answer is Option A.
Q4: A sub-atomic particle of mass ????
-????
???? is moving with a velocity ?? .???? ×
????
?? ?? /?? . Under the matter wave consideration, the particle will behave closely like
(?? = ?? .???? × ????
-????
?? .?? )
JEE Main 2025 (Online) 23rd January Morning Shift
Options:
A. X-rays
B. Infra-red radiation
C. Gamma rays
D. Visible radiation
Ans: A
Solution:
To find the matter wave behavior of the particle, we use the de Broglie wavelength formula:
?? =
h
????
where:
h= 6.63× 10
-34
J · s is Planck's constant,
?? = 10
-30
kg is the mass of the particle, and
?? = 2.21× 10
6
m/s is its velocity.
Follow these steps:
Substitute the values into the formula:
?? =
6.63× 10
-34
(10
-30
)(2.21× 10
6
)
Calculate the denominator:
10
-30
× 2.21× 10
6
= 2.21× 10
-24
Now compute the wavelength:
?? ˜
6.63× 10
-34
2.21× 10
-24
˜ 3 × 10
-10
m
This wavelength, roughly 3 × 10
-10
m (or 0.3 nm ), lies within the X-ray portion of the
electromagnetic spectrum, since X-rays typically have wavelengths in the range of about 0.01
nm to 10 nm .
Therefore, under the matter wave consideration, the particle will behave closely like:
Option A: X-rays.
Q5: In photoelectric effect an em-wave is incident on a metal surface and electrons
are ejected from the surface. If the work function of the metal is 2.14 eV and stopping
potential is 2 V , what is the wavelength of the em-wave?(Given ???? = ???????? ????????
where ?? is the Planck's constant and ?? is the speed of light in vaccum.)
JEE Main 2025 (Online) 23rd January Evening Shift
Options:
A. 400 nm
B. 600 nm
C. 300 nm
D. 200 nm
Ans: C
Solution:
Let's break down the problem step by step:
In the photoelectric effect, the energy of a photon is given by:
h?? = ?? + ?? ??
where:
?? is the work function of the metal,
?? ?? is the kinetic energy of the ejected electron.
The kinetic energy of the ejected electrons is provided by the stopping potential:
?? ?? = ????
Given that the stopping potential is ?? = 2 V, we have:
?? ?? = 2eV
Now, we can calculate the photon energy:
h?? = ?? + ?? ?? = 2.14eV+ 2eV= 4.14eV
The relation between the photon's energy and its wavelength is:
h?? =
h?? ??
Rearranging for ?? :
?? =
h?? h??
Given that h?? = 1242eV· nm , substitute the values:
?? =
1242eV· nm
4.14eV
Calculate the wavelength:
?? ˜
1242
4.14
˜ 300 nm
Thus, the wavelength of the incident electromagnetic wave is approximately 300 nm .
The correct answer is Option C: 300 nm .
Q6: An electron of mass ' ?? ' with an initial velocity ??? = ?? ?? ??ˆ(?? ?? > ?? ) enters an electric
field ?? ? ?
= -?? ?? ?? ˆ
. If the initial de Broglie wavelength is ?? ?? , the value after time ?? would
be
JEE Main 2025 (Online) 24th January Morning Shift
Options:
Page 5
JEE Main Previous Year Questions
(2025): Dual Nature of Matter and
Radiation
Q1: An electron in the ground state of the hydrogen atom has the orbital radius of
?? .?? × ????
-????
?? while that for the electron in third excited state is ?? .???? × ????
-????
?? .
The ratio of the de Broglie wavelengths of electron in the ground state to that in the
excited state is
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. 4
B. 3
C. 9
D. 16
Ans: A
Solution:
We know, ?? =
h
????
and ?????? =
?? h
2??
? ???? =
?? h
2????
So, ?? =
h
?? h
2???? = 2?? ?? ??
? ?? ?
?? ??
We can write,
?? ?? ?? ?? = (
?? ?? ?? ?? )(
?? ?? ?? ?? )
?
?? ?? ?? ?? = (
5.3× 10
-11
84.8× 10
-11
)(
4
1
) =
1
4
?
?? ?? ?? ?? = 4
Q2: The work functions of cesium ( Cs ) and lithium ( Li ) metals are 1.9 eV and 2.5 eV ,
respectively. If we incident a light of wavelength 550 nm on these two metal surfaces,
then photo-electric effect is possible for the case of
JEE Main 2025 (Online) 22nd January Morning Shift
Options:
A. Both Cs and Li
B. Neither Cs nor Li
C. Li only
D. Cs only
Ans: D
Solution:
For photo-electric effect, energy of the photon must be greater than the work function of the
metal.
We know, ?? =
1240
?? =
1240
550
(as ?? = 550 nm given)
? ?? = 2.25eV
here, ?? > ?? ????
So, ?? ?? only.
Q3: A light source of wavelength ?? illuminates a metal surface and electrons are
ejected with maximum kinetic energy of 2 eV . If the same surface is illuminated by a
light source of wavelength
?? ?? , then the maximum kinetic energy of ejected electrons
will be (The work function of metal is ?? ???? )
JEE Main 2025 (Online) 22nd January Evening Shift
Options:
A. 5 eV
B. 3 eV
C. 2 eV
D. 6 eV
Ans: A
Solution:
Let's break down the problem step by step.
The photoelectric equation is given by:
?? max
=
h?? ?? - ??
where:
?? max
is the maximum kinetic energy of the electrons.
h?? ?? is the energy of the incident photon.
?? is the work function of the metal.
For the initial light source of wavelength ?? , we know:
2eV=
h?? ?? - 1eV
Solving for
h?? ?? gives:
h?? ?? = 2eV+ 1eV= 3eV
Now, if the wavelength is halved to
?? 2
, the photon energy becomes:
h?? ?? /2
=
2h?? ?? = 2× 3eV= 6eV
The maximum kinetic energy for the new wavelength is then:
?? max
'
= 6eV- 1eV= 5eV
Therefore, the maximum kinetic energy of the ejected electrons when the surface is illuminated
by a light source of wavelength
?? 2
is 5 eV .
The correct answer is Option A.
Q4: A sub-atomic particle of mass ????
-????
???? is moving with a velocity ?? .???? ×
????
?? ?? /?? . Under the matter wave consideration, the particle will behave closely like
(?? = ?? .???? × ????
-????
?? .?? )
JEE Main 2025 (Online) 23rd January Morning Shift
Options:
A. X-rays
B. Infra-red radiation
C. Gamma rays
D. Visible radiation
Ans: A
Solution:
To find the matter wave behavior of the particle, we use the de Broglie wavelength formula:
?? =
h
????
where:
h= 6.63× 10
-34
J · s is Planck's constant,
?? = 10
-30
kg is the mass of the particle, and
?? = 2.21× 10
6
m/s is its velocity.
Follow these steps:
Substitute the values into the formula:
?? =
6.63× 10
-34
(10
-30
)(2.21× 10
6
)
Calculate the denominator:
10
-30
× 2.21× 10
6
= 2.21× 10
-24
Now compute the wavelength:
?? ˜
6.63× 10
-34
2.21× 10
-24
˜ 3 × 10
-10
m
This wavelength, roughly 3 × 10
-10
m (or 0.3 nm ), lies within the X-ray portion of the
electromagnetic spectrum, since X-rays typically have wavelengths in the range of about 0.01
nm to 10 nm .
Therefore, under the matter wave consideration, the particle will behave closely like:
Option A: X-rays.
Q5: In photoelectric effect an em-wave is incident on a metal surface and electrons
are ejected from the surface. If the work function of the metal is 2.14 eV and stopping
potential is 2 V , what is the wavelength of the em-wave?(Given ???? = ???????? ????????
where ?? is the Planck's constant and ?? is the speed of light in vaccum.)
JEE Main 2025 (Online) 23rd January Evening Shift
Options:
A. 400 nm
B. 600 nm
C. 300 nm
D. 200 nm
Ans: C
Solution:
Let's break down the problem step by step:
In the photoelectric effect, the energy of a photon is given by:
h?? = ?? + ?? ??
where:
?? is the work function of the metal,
?? ?? is the kinetic energy of the ejected electron.
The kinetic energy of the ejected electrons is provided by the stopping potential:
?? ?? = ????
Given that the stopping potential is ?? = 2 V, we have:
?? ?? = 2eV
Now, we can calculate the photon energy:
h?? = ?? + ?? ?? = 2.14eV+ 2eV= 4.14eV
The relation between the photon's energy and its wavelength is:
h?? =
h?? ??
Rearranging for ?? :
?? =
h?? h??
Given that h?? = 1242eV· nm , substitute the values:
?? =
1242eV· nm
4.14eV
Calculate the wavelength:
?? ˜
1242
4.14
˜ 300 nm
Thus, the wavelength of the incident electromagnetic wave is approximately 300 nm .
The correct answer is Option C: 300 nm .
Q6: An electron of mass ' ?? ' with an initial velocity ??? = ?? ?? ??ˆ(?? ?? > ?? ) enters an electric
field ?? ? ?
= -?? ?? ?? ˆ
. If the initial de Broglie wavelength is ?? ?? , the value after time ?? would
be
JEE Main 2025 (Online) 24th January Morning Shift
Options:
A.
?? ?? v1-
e
2
E
o
2
?? 2
m
2
v
o
2
B. ?? 0
C.
?? ?? v1+
e
2
E
o
2
t
2
m
2
?? ?? 2
D. ?? o
v1+
e
2
E
o
2
t
2
m
2
v
o
2
Ans: C
Solution:
Derivation of the de Broglie wavelength after time ??
The de Broglie wavelength is given by
?? =
h
?? ,
where h is Planck's constant and ?? is the momentum of the particle.
Initial Conditions:
Initially, the electron has a velocity
?? = ?? 0
??ˆ,
so its momentum is
?? 0
= ?? ?? 0
.
The initial de Broglie wavelength is therefore
?? 0
=
h
?? ?? 0
.
Effect of the Electric Field:
The electron enters an electric field
?? ?
= -?? 0
?? ˆ
.
For an electron with charge -?? , the force is given by
??
= -?? ?? ?
= -?? (-?? 0
?? ˆ
)= ?? ?? 0
?? ˆ
This force causes an acceleration in the ?? ˆ
direction:
?? ?? =
?? ?? ?? =
?? ?? 0
?? .
Momentum Components After Time ?? :
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