Magnetism and Matter: JEE Main Previous Year Questions (2021-2026)

 Page 1


JEE Main Previous Year Questions (2021-2026): 
Magnetism and Matter  
 
(January 2026) 
 
Q1: Given below are two statements: one is labelled as Assertion (A) and the other is 
labelled as Reason (R).  
Consider a ferromagnetic material :  
Assertion (A): The individual atoms in a ferromagnetic material possess a magnetic 
dipole moment and interact with one another in such a way that they spontaneously align 
themselves forming domains.  
Reason (R): At high enough temperature, the domain structure of ferromagnetic material 
disintegrates. Thus, magnetization will disappear at high enough temperature known as 
Curie temperature.  
In the light of the above statements, choose the correct answer from the options given 
below :  
(a) (A) is true but (R) is false  
(b) Both (A) and (R) are true and (R) is the correct explanation of (A)  
(c) (A) is false but (R) is true  
(d)  Both (A) and (R) are true but (R) is not the correct explanation of (A) 
Ans: (d) 
Sol:  
Ferromagnetic materials (like iron, nickel, cobalt) are characterized by the fact that their 
individual atoms possess a permanent magnetic dipole moment. Due to strong quantum 
mechanical interactions between neighbouring atoms, these dipoles spontaneously align 
parallel to each other within small macroscopic regions. 
These aligned regions are indeed called magnetic domains. Within a domain, the magnetization 
is saturated, even in the absence of an external field. 
Page 2


JEE Main Previous Year Questions (2021-2026): 
Magnetism and Matter  
 
(January 2026) 
 
Q1: Given below are two statements: one is labelled as Assertion (A) and the other is 
labelled as Reason (R).  
Consider a ferromagnetic material :  
Assertion (A): The individual atoms in a ferromagnetic material possess a magnetic 
dipole moment and interact with one another in such a way that they spontaneously align 
themselves forming domains.  
Reason (R): At high enough temperature, the domain structure of ferromagnetic material 
disintegrates. Thus, magnetization will disappear at high enough temperature known as 
Curie temperature.  
In the light of the above statements, choose the correct answer from the options given 
below :  
(a) (A) is true but (R) is false  
(b) Both (A) and (R) are true and (R) is the correct explanation of (A)  
(c) (A) is false but (R) is true  
(d)  Both (A) and (R) are true but (R) is not the correct explanation of (A) 
Ans: (d) 
Sol:  
Ferromagnetic materials (like iron, nickel, cobalt) are characterized by the fact that their 
individual atoms possess a permanent magnetic dipole moment. Due to strong quantum 
mechanical interactions between neighbouring atoms, these dipoles spontaneously align 
parallel to each other within small macroscopic regions. 
These aligned regions are indeed called magnetic domains. Within a domain, the magnetization 
is saturated, even in the absence of an external field. 
 
Hence, the Assertion (A) is True.  
Temperature represents thermal agitation. As the temperature of a ferromagnetic material 
increases, the thermal energy tends to randomize the orientation of the magnetic dipoles.  
At a specific critical temperature called the Curie Temperature (T
c
), the thermal agitation 
becomes strong enough to overcome the exchange coupling that holds the domains together. 
The domain structure breaks down (disintegrates), and the material transitions from 
ferromagnetic to paramagnetic, losing its spontaneous magnetization.  
So, the Reason (R) is also True.  
The formation of domains (A) is caused by the minimization of exchange energy and 
magnetostatic energy. The destruction of domains at high temperature (R) is a property of the 
material's phase transition. Knowing that domains disappear at high heat does not explain the 
fundamental physical mechanism (exchange interaction) that causes them to align 
spontaneously at lower temperatures.  
Both statements are correct facts, but R is not the functional explanation for A , i.e., both (A) and 
(R) are true but (R) is not the correct explanation of (A).  
Hence, the correct option is (D). 
 
Q2: A short bar magnet placed with its axis at 30
°
 with an external field of 800 Gauss, 
experiences a torque of 0.016 N. m. The work done in moving it from most stable to most 
unstable position is a × 10
-3
 J. The value of a is_____. 
Ans: 64 
Sol: 
Page 3


JEE Main Previous Year Questions (2021-2026): 
Magnetism and Matter  
 
(January 2026) 
 
Q1: Given below are two statements: one is labelled as Assertion (A) and the other is 
labelled as Reason (R).  
Consider a ferromagnetic material :  
Assertion (A): The individual atoms in a ferromagnetic material possess a magnetic 
dipole moment and interact with one another in such a way that they spontaneously align 
themselves forming domains.  
Reason (R): At high enough temperature, the domain structure of ferromagnetic material 
disintegrates. Thus, magnetization will disappear at high enough temperature known as 
Curie temperature.  
In the light of the above statements, choose the correct answer from the options given 
below :  
(a) (A) is true but (R) is false  
(b) Both (A) and (R) are true and (R) is the correct explanation of (A)  
(c) (A) is false but (R) is true  
(d)  Both (A) and (R) are true but (R) is not the correct explanation of (A) 
Ans: (d) 
Sol:  
Ferromagnetic materials (like iron, nickel, cobalt) are characterized by the fact that their 
individual atoms possess a permanent magnetic dipole moment. Due to strong quantum 
mechanical interactions between neighbouring atoms, these dipoles spontaneously align 
parallel to each other within small macroscopic regions. 
These aligned regions are indeed called magnetic domains. Within a domain, the magnetization 
is saturated, even in the absence of an external field. 
 
Hence, the Assertion (A) is True.  
Temperature represents thermal agitation. As the temperature of a ferromagnetic material 
increases, the thermal energy tends to randomize the orientation of the magnetic dipoles.  
At a specific critical temperature called the Curie Temperature (T
c
), the thermal agitation 
becomes strong enough to overcome the exchange coupling that holds the domains together. 
The domain structure breaks down (disintegrates), and the material transitions from 
ferromagnetic to paramagnetic, losing its spontaneous magnetization.  
So, the Reason (R) is also True.  
The formation of domains (A) is caused by the minimization of exchange energy and 
magnetostatic energy. The destruction of domains at high temperature (R) is a property of the 
material's phase transition. Knowing that domains disappear at high heat does not explain the 
fundamental physical mechanism (exchange interaction) that causes them to align 
spontaneously at lower temperatures.  
Both statements are correct facts, but R is not the functional explanation for A , i.e., both (A) and 
(R) are true but (R) is not the correct explanation of (A).  
Hence, the correct option is (D). 
 
Q2: A short bar magnet placed with its axis at 30
°
 with an external field of 800 Gauss, 
experiences a torque of 0.016 N. m. The work done in moving it from most stable to most 
unstable position is a × 10
-3
 J. The value of a is_____. 
Ans: 64 
Sol: 
 
When a magnetic dipole like a bar magnet is placed in a magnetic field (B) at an angle ( ? ), it 
experiences a torque.  
t = M B sin   ?  
Where, M = magnetic moment of the magnet, B = magnetic field strength, ? = Angle between 
the magnet's axis and the field.  
The magnetic field is given in Gauss. We must convert it to the standard SI unit, Tesla (T). 
 
The potential energy of the magnetic dipole is given as U = - MB cos   ?  
The magnet is aligned with the magnetic field, i.e., ?
1
 = 0
°
.  
The potential energy is minimum. The magnet is aligned against (opposite to) the magnetic 
field, i.e., ?
2
 = 180
°
. The potential energy is maximum.  
The work done to rotate a magnet from an initial angle ?
1
 to a final angle ?
2
 is equal to the 
change in its potential energy. 
Page 4


JEE Main Previous Year Questions (2021-2026): 
Magnetism and Matter  
 
(January 2026) 
 
Q1: Given below are two statements: one is labelled as Assertion (A) and the other is 
labelled as Reason (R).  
Consider a ferromagnetic material :  
Assertion (A): The individual atoms in a ferromagnetic material possess a magnetic 
dipole moment and interact with one another in such a way that they spontaneously align 
themselves forming domains.  
Reason (R): At high enough temperature, the domain structure of ferromagnetic material 
disintegrates. Thus, magnetization will disappear at high enough temperature known as 
Curie temperature.  
In the light of the above statements, choose the correct answer from the options given 
below :  
(a) (A) is true but (R) is false  
(b) Both (A) and (R) are true and (R) is the correct explanation of (A)  
(c) (A) is false but (R) is true  
(d)  Both (A) and (R) are true but (R) is not the correct explanation of (A) 
Ans: (d) 
Sol:  
Ferromagnetic materials (like iron, nickel, cobalt) are characterized by the fact that their 
individual atoms possess a permanent magnetic dipole moment. Due to strong quantum 
mechanical interactions between neighbouring atoms, these dipoles spontaneously align 
parallel to each other within small macroscopic regions. 
These aligned regions are indeed called magnetic domains. Within a domain, the magnetization 
is saturated, even in the absence of an external field. 
 
Hence, the Assertion (A) is True.  
Temperature represents thermal agitation. As the temperature of a ferromagnetic material 
increases, the thermal energy tends to randomize the orientation of the magnetic dipoles.  
At a specific critical temperature called the Curie Temperature (T
c
), the thermal agitation 
becomes strong enough to overcome the exchange coupling that holds the domains together. 
The domain structure breaks down (disintegrates), and the material transitions from 
ferromagnetic to paramagnetic, losing its spontaneous magnetization.  
So, the Reason (R) is also True.  
The formation of domains (A) is caused by the minimization of exchange energy and 
magnetostatic energy. The destruction of domains at high temperature (R) is a property of the 
material's phase transition. Knowing that domains disappear at high heat does not explain the 
fundamental physical mechanism (exchange interaction) that causes them to align 
spontaneously at lower temperatures.  
Both statements are correct facts, but R is not the functional explanation for A , i.e., both (A) and 
(R) are true but (R) is not the correct explanation of (A).  
Hence, the correct option is (D). 
 
Q2: A short bar magnet placed with its axis at 30
°
 with an external field of 800 Gauss, 
experiences a torque of 0.016 N. m. The work done in moving it from most stable to most 
unstable position is a × 10
-3
 J. The value of a is_____. 
Ans: 64 
Sol: 
 
When a magnetic dipole like a bar magnet is placed in a magnetic field (B) at an angle ( ? ), it 
experiences a torque.  
t = M B sin   ?  
Where, M = magnetic moment of the magnet, B = magnetic field strength, ? = Angle between 
the magnet's axis and the field.  
The magnetic field is given in Gauss. We must convert it to the standard SI unit, Tesla (T). 
 
The potential energy of the magnetic dipole is given as U = - MB cos   ?  
The magnet is aligned with the magnetic field, i.e., ?
1
 = 0
°
.  
The potential energy is minimum. The magnet is aligned against (opposite to) the magnetic 
field, i.e., ?
2
 = 180
°
. The potential energy is maximum.  
The work done to rotate a magnet from an initial angle ?
1
 to a final angle ?
2
 is equal to the 
change in its potential energy. 
 
So, the work done is, 
 
Page 5


JEE Main Previous Year Questions (2021-2026): 
Magnetism and Matter  
 
(January 2026) 
 
Q1: Given below are two statements: one is labelled as Assertion (A) and the other is 
labelled as Reason (R).  
Consider a ferromagnetic material :  
Assertion (A): The individual atoms in a ferromagnetic material possess a magnetic 
dipole moment and interact with one another in such a way that they spontaneously align 
themselves forming domains.  
Reason (R): At high enough temperature, the domain structure of ferromagnetic material 
disintegrates. Thus, magnetization will disappear at high enough temperature known as 
Curie temperature.  
In the light of the above statements, choose the correct answer from the options given 
below :  
(a) (A) is true but (R) is false  
(b) Both (A) and (R) are true and (R) is the correct explanation of (A)  
(c) (A) is false but (R) is true  
(d)  Both (A) and (R) are true but (R) is not the correct explanation of (A) 
Ans: (d) 
Sol:  
Ferromagnetic materials (like iron, nickel, cobalt) are characterized by the fact that their 
individual atoms possess a permanent magnetic dipole moment. Due to strong quantum 
mechanical interactions between neighbouring atoms, these dipoles spontaneously align 
parallel to each other within small macroscopic regions. 
These aligned regions are indeed called magnetic domains. Within a domain, the magnetization 
is saturated, even in the absence of an external field. 
 
Hence, the Assertion (A) is True.  
Temperature represents thermal agitation. As the temperature of a ferromagnetic material 
increases, the thermal energy tends to randomize the orientation of the magnetic dipoles.  
At a specific critical temperature called the Curie Temperature (T
c
), the thermal agitation 
becomes strong enough to overcome the exchange coupling that holds the domains together. 
The domain structure breaks down (disintegrates), and the material transitions from 
ferromagnetic to paramagnetic, losing its spontaneous magnetization.  
So, the Reason (R) is also True.  
The formation of domains (A) is caused by the minimization of exchange energy and 
magnetostatic energy. The destruction of domains at high temperature (R) is a property of the 
material's phase transition. Knowing that domains disappear at high heat does not explain the 
fundamental physical mechanism (exchange interaction) that causes them to align 
spontaneously at lower temperatures.  
Both statements are correct facts, but R is not the functional explanation for A , i.e., both (A) and 
(R) are true but (R) is not the correct explanation of (A).  
Hence, the correct option is (D). 
 
Q2: A short bar magnet placed with its axis at 30
°
 with an external field of 800 Gauss, 
experiences a torque of 0.016 N. m. The work done in moving it from most stable to most 
unstable position is a × 10
-3
 J. The value of a is_____. 
Ans: 64 
Sol: 
 
When a magnetic dipole like a bar magnet is placed in a magnetic field (B) at an angle ( ? ), it 
experiences a torque.  
t = M B sin   ?  
Where, M = magnetic moment of the magnet, B = magnetic field strength, ? = Angle between 
the magnet's axis and the field.  
The magnetic field is given in Gauss. We must convert it to the standard SI unit, Tesla (T). 
 
The potential energy of the magnetic dipole is given as U = - MB cos   ?  
The magnet is aligned with the magnetic field, i.e., ?
1
 = 0
°
.  
The potential energy is minimum. The magnet is aligned against (opposite to) the magnetic 
field, i.e., ?
2
 = 180
°
. The potential energy is maximum.  
The work done to rotate a magnet from an initial angle ?
1
 to a final angle ?
2
 is equal to the 
change in its potential energy. 
 
So, the work done is, 
 
 
Q1: Match List - I with List - II. 
List - I List - II 
(A) Magnetic induction (I) Ampere meter  
?? 
(B) Magnetic intensity (II) Weber 
(C) Magnetic flux (III) Gauss 
(D) Magnetic moment (IV) Ampere meter 
Choose the correct answer from the options given below: 
JEE Main 2025 (Online) 29th January Evening Shift 
Options: 
A. (A)-(III), (B)-(IV), (C)-(II), (D)-(I) 
B. (A)-(III), (B)-(II), (C)-(I), (D)-(IV) 
C. (A)-(III), (B)-(IV), (C)-(I), (D)-(II) 
D. (A)-(I), (B)-(II), (C)-(III), (D)-(IV) 
Ans: A 
Solution: 
(A) The unit "gauss" is used to measure magnetic induction, also known as magnetic flux 
density, within the CGS system of units. 
?? =
?? ?? =
max well 
?? ?? 2
= gauss (CGS) 
(B) Magnetic intensity ( H ) is defined as the product of the number of turns per unit length in a 
coil ( n ) and the current that it carries (I). 
i.e. ?? = ???? =
?? ?? ?? 
Unit : A/m or Am
-1
 
(C) Magnetic flux, ?? = ???? 
unit : weber 
(D) Magnetic moment (M) : magnetic moment of a current loop, ?? = ?????? 
where, N = number of turns 
I = current 
A = Area 
So, unit = Am
2
 
Hence, option A is correct.