Maxwell’s Equations; Magnetism of Matter Problems
This section provides 100 problems to test your understanding of Maxwell’s equations and the magnetism of matter, including calculations of electric and magnetic fields, induced emf, displacement current, and magnetic properties of materials. Inspired by JEE Main, JEE Advanced, and NEET exam patterns, these problems are tailored for exam preparation, offering a mix of numerical, conceptual, and derivation-based challenges. NEET-style problems (66–100) are formatted as multiple-choice questions (MCQs) to match the exam’s objective format. Problems are organized by type to support progressive learning and build confidence in mastering electromagnetism, a key topic for JEE/NEET success.
Numerical Problems
A point charge
is at the center of a spherical Gaussian surface with radius . Calculate the electric field at the surface ( ). - (a)
- (b)
- (c)
- (d)
- (a)
An infinite sheet has a surface charge density
. Calculate the electric field near the sheet. - (a)
- (b)
- (c)
- (d)
- (a)
An infinite line charge has
. Calculate at a distance . - (a)
- (b)
- (c)
- (d)
- (a)
A spherical shell with uniform charge density
has radius . Calculate at inside. - (a)
- (b)
- (c)
- (d)
- (a)
A bar magnet is enclosed in a spherical Gaussian surface. Calculate the net magnetic flux through the surface.
- (a)
- (b)
- (c)
- (d)
- (a)
A loop with area
is in a magnetic field (increasing). Calculate the induced emf at . - (a)
- (b)
- (c)
- (d)
- (a)
A solenoid with
turns, , has increasing at . Calculate the induced emf. - (a)
- (b)
- (c)
- (d)
- (a)
A capacitor with plates of area
, separation , has increasing at . Calculate the displacement current. - (a)
- (b)
- (c)
- (d)
- (a)
A material has magnetic susceptibility
. Calculate the relative permeability . - (a)
- (b)
- (c)
- (d)
- (a)
A paramagnetic material has
. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A ferromagnetic material with
is in a solenoid with . Calculate ( ). - (a)
- (b)
- (c)
- (d)
- (a)
A hysteresis loop for a ferromagnetic material has an area of
per cycle, and the material volume is . Calculate the energy loss per cycle. - (a)
- (b)
- (c)
- (d)
- (a)
A point charge
is at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
An infinite sheet with
. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A line charge
at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A spherical shell
, , at inside. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A closed surface encloses a solenoid with
inside. Calculate the net magnetic flux. - (a)
- (b)
- (c)
- (d)
- (a)
A loop
in (increasing). Calculate at . - (a)
- (b)
- (c)
- (d)
- (a)
A solenoid
, , increasing at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A capacitor
, , increasing at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A material
. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A material
. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A material
, . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A hysteresis loop area
, volume . Calculate energy loss per cycle. - (a)
- (b)
- (c)
- (d)
- (a)
A point charge
at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
An infinite sheet
. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A line charge
at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A spherical shell
, , at inside. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A loop
in (increasing). Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A solenoid
, , increasing at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A spacecraft capacitor
, , increasing at . Calculate for shielding analysis. - (a)
- (b)
- (c)
- (d)
- (a)
A material
. Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A material
, . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
A hysteresis loop area
, volume . Calculate energy loss per cycle. - (a)
- (b)
- (c)
- (d)
- (a)
A point charge
at . Calculate . - (a)
- (b)
- (c)
- (d)
- (a)
Conceptual Problems
- What does Gauss’s law for electricity relate?
- (a) Magnetic field to enclosed current
- (b) Electric field to enclosed charge
- (c) Magnetic field to enclosed charge
- (d) Electric field to enclosed current
- What does Gauss’s law for magnetism imply?
- (a) Existence of magnetic monopoles
- (b) No magnetic monopoles exist
- (c) Electric field lines are closed
- (d) Magnetic field is zero everywhere
- What is the unit of electric flux in SI units?
- (a) N·m²/C
- (b) T·m²
- (c) A/m
- (d) V/m
- What happens to the magnetic flux through a closed surface if a magnetic monopole existed?
- (a) It would be zero
- (b) It would be non-zero
- (c) It would be infinite
- (d) It would depend on the surface shape
- What does Faraday’s law describe?
- (a) Induced emf due to changing electric flux
- (b) Induced emf due to changing magnetic flux
- (c) Magnetic field due to enclosed charge
- (d) Electric field due to enclosed current
- What does the Ampere-Maxwell law include that Ampere’s law does not?
- (a) Conduction current
- (b) Displacement current
- (c) Magnetic flux
- (d) Electric charge
- What is the unit of magnetic susceptibility
?
- (a) Henry
- (b) Dimensionless
- (c) A/m
- (d) T
- What happens to the magnetic field
inside a diamagnetic material?
- (a) Increases
- (b) Decreases
- (c) Remains unchanged
- (d) Becomes zero
- What does a large positive
indicate about a material?
- (a) Diamagnetic
- (b) Paramagnetic
- (c) Ferromagnetic
- (d) Non-magnetic
- What is the dimension of magnetic field intensity
?
- (a)
- (b)
- (c)
- (d)
- What does a zero net magnetic flux through a closed surface indicate?
- (a) Presence of a magnetic monopole
- (b) Absence of magnetic monopoles
- (c) No magnetic field
- (d) No electric field
- What is the significance of
?
- (a) Magnetic flux through a surface
- (b) Electric flux through a closed surface
- (c) Induced emf in a loop
- (d) Displacement current
- What does the displacement current in the Ampere-Maxwell law account for?
- (a) Changing magnetic field
- (b) Changing electric field
- (c) Static electric field
- (d) Static magnetic field
- What does a negative
indicate about a material?
- (a) Paramagnetic
- (b) Ferromagnetic
- (c) Diamagnetic
- (d) Non-magnetic
- How does ferromagnetism assist in spacecraft shielding?
- (a) Increases electric field
- (b) Enhances magnetic field shielding
- (c) Reduces magnetic susceptibility
- (d) Increases electric flux
Derivation Problems
Derive the electric field due to a point charge using Gauss’s law
. Derive the electric field due to an infinite sheet
. Derive the electric field due to an infinite line charge
. Derive the electric field inside a uniformly charged spherical shell using Gauss’s law.
Derive the magnetic flux through a closed surface using Gauss’s law for magnetism
. Derive the induced emf in a loop due to a changing magnetic field using Faraday’s law
. Derive the displacement current in a charging capacitor using the Ampere-Maxwell law.
Derive the magnetic field
in a material using . Derive the relationship between
and for a material . Derive the electric field due to a uniformly charged sphere outside the sphere.
Derive the magnetic field inside a solenoid using the Ampere-Maxwell law.
Derive the energy loss per cycle in a hysteresis loop for a ferromagnetic material.
Derive the electric flux through a Gaussian surface enclosing multiple charges.
Derive the induced electric field around a loop using Faraday’s law
. Derive the magnetization
in a material using .
NEET-style Conceptual Problems
- What is the unit of magnetic flux in SI units?
- (a) Weber
- (b) Tesla
- (c) Henry
- (d) Volt
- What does a non-zero electric flux through a closed surface indicate?
- (a) No charge enclosed
- (b) Net charge enclosed
- (c) No electric field
- (d) No magnetic field
- What is the relationship between electric field and enclosed charge in Gauss’s law?
- (a)
- (b)
- (c)
is independent of - (d)
- What happens to the magnetic flux through a closed surface if a magnetic dipole is enclosed?
- (a) Becomes non-zero
- (b) Remains zero
- (c) Becomes infinite
- (d) Depends on the dipole strength
- What is the dimension of
?
- (a)
- (b)
- (c)
- (d)
- What does the induced emf in a loop depend on according to Faraday’s law?
- (a) Rate of change of electric flux
- (b) Rate of change of magnetic flux
- (c) Static magnetic field
- (d) Static electric field
- What is the role of displacement current in the Ampere-Maxwell law?
- (a) Accounts for static electric fields
- (b) Accounts for changing electric fields
- (c) Reduces magnetic field
- (d) Increases conduction current
- What happens to the magnetic field inside a paramagnetic material?
- (a) Decreases
- (b) Increases slightly
- (c) Becomes zero
- (d) Becomes infinite
- Why does a ferromagnetic material exhibit hysteresis?
.ConcurrentModificationException: (a) Due to alignment of magnetic domains
- (b) Due to static magnetic fields
- (c) Due to electric fields
- (d) Due to diamagnetism
- What is the unit of magnetization
?
- (a) A/m
- (b) T
- (c) H/m
- (d) V/m
- What does a constant electric field inside a conductor indicate?
- (a) Non-zero flux
- (b) Zero flux
- (c) No charges
- (d) Static charges
- Which type of material has a large susceptibility
?
- (a) Diamagnetic
- (b) Paramagnetic
- (c) Ferromagnetic
- (d) Non-magnetic
- What is the direction of the induced electric field in Faraday’s law?
- (a) Along the magnetic field
- (b) Perpendicular to the changing magnetic flux
- (c) Random
- (d) Zero
- What does a pseudo-force do in a non-inertial frame for Maxwell’s equations?
- (a) Affects perceived fields
- (b) Affects charge distribution
- (c) Creates magnetic monopoles
- (d) Reduces susceptibility
- What is the dimension of
?
- (a)
- (b)
- (c)
- (d)
- What is the role of ferromagnetic materials in spacecraft shielding?
- (a) Increase electric field
- (b) Enhance magnetic field shielding
- (c) Reduce voltage
- (d) Increase resistance
- What happens to the electric field inside a conductor in electrostatic equilibrium?
- (a) Becomes non-zero
- (b) Becomes zero
- (c) Increases
- (d) Decreases
- Why does the Ampere-Maxwell law include displacement current?
- (a) To account for static fields
- (b) To ensure continuity of magnetic fields
- (c) To reduce electric flux
- (d) To increase conduction current
- What is the significance of
?
- (a) Electric permittivity
- (b) Magnetic permeability of a material
- (c) Induced emf
- (d) Displacement current
- What is the unit of displacement current?
- (a) Ampere
- (b) Volt
- (c) Tesla
- (d) Weber
- What does a zero induced emf in a loop indicate?
- (a) No magnetic field
- (b) No change in magnetic flux
- (c) Infinite flux
- (d) No electric field
- What is the physical significance of
?
- (a) Electric field due to an infinite sheet
- (b) Magnetic field due to a current
- (c) Induced emf in a loop
- (d) Displacement current
- Why does the magnetic field inside a diamagnetic material decrease?
- (a) Due to positive
- (b) Due to negative
- (c) Due to increased
- (d) Due to decreased
- What is the dimension of
?
- (a)
- (b)
- (c)
- (d)
- How does the displacement current assist in spacecraft communication?
- (a) Increases voltage
- (b) Ensures field continuity in capacitors
- (c) Reduces current
- (d) Increases resistance
- What is the role of enclosed charge in Gauss’s law for electricity?
- (a)
- (b)
- (c) No dependence
- (d) Exponential dependence
- What does a high
in a material indicate?
- (a) Diamagnetic
- (b) Paramagnetic
- (c) Ferromagnetic
- (d) Non-magnetic
- What is the physical significance of
?
- (a) Conduction current
- (b) Displacement current
- (c) Induced emf
- (d) Magnetic flux
- What is the dimension of
?
- (a)
- (b)
- (c)
- (d)
- Why does a ferromagnetic material have a high susceptibility?
- (a) Due to alignment of magnetic domains
- (b) Due to static fields
- (c) Due to diamagnetic properties
- (d) Due to low
NEET-style Numerical Problems
- A point charge
at . Calculate .
- (a)
- (b)
- (c)
- (d)
- A loop
in (increasing). Calculate .
- (a)
- (b)
- (c)
- (d)
- A solenoid
, , increasing at . Calculate .
- (a)
- (b)
- (c)
- (d)
- A capacitor
, , increasing at . Calculate .
- (a)
- (b)
- (c)
- (d)
- A material
, . Calculate .
- (a)
- (b)
- (c)
- (d)