EASY
UPES B.Tech Admissions 2025
Ranked #42 among Engineering colleges in India by NIRF | Highest Package 1.3 CR , 100% Placements | Last Date to Apply: 15th May
Gauss Law Of Magnetism - Practice Questions & MCQ
Edited By admin | Updated on Sep 18, 2023 18:34 AM | #JEE Main
Quick Facts
-
18 Questions around this concept.
Solve by difficulty
Gauss law for magnetic field is given by
Curie temperature is the temperature above which
$q_1, q_2, q_3, q_4$ are point charges located at points as shown in the figure and s is a spherical Gaussian surface of radius $R$. Which of the following is true according to Gauss's law
Electric charge is uniformly distributed along a long straight wire of radius 1 mm. The charge per cm length of the wire is Q coulomb. Another cylindrical surface of radius 50 cm and length 1 m symmetrically encloses the wire as shown in the figure. The total electric flux passing through the cylindrical surface is
The Gauss's law of magnetism is represented by:
The Gauss's law of magnetism is represented by
Direction: In the following question, a statement of Assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
Assertion: Magnetic flux enclosed with a closed surface is always zero.
Reason: For both electric field and magnetic field Gauss theory is applicable.
Consider the two idealized systems: (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length L >> R, the radius of the cross-section.
In (i) E is ideally treated as a constant between plates and zero outside.
In (ii) the magnetic field is constant inside the solenoid and zero outside.
These idealized assumptions, however, contradict fundamental laws as below:
Concepts Covered - 1
Magnetism and gauss's law
Magnetic flux (f)-
It is defined as the magnetic lines of force passing normally through a surface called magnetic flux.
As we learn in electrostatic, the Gauss law for a closed surface states that :
$
\begin{aligned}
& \phi_{\text {closed }}=\frac{q_{\text {net }}}{\epsilon_0} \\
& \text { where }
\end{aligned}
$
S is the area enclosed and E is the electric field intensity passing through it. and $q_{n e t}$ is the total charge inside the closed surface.
But Gauss's Law of magnetism states that the flux of the magnetic field through any closed surface is zero (as shown in the below figure).
It is because inside the closed surface simplest magnetic element is a magnetic dipole with both the poles (since magnet with monopole does not exist). So a number of magnetic field lines entering the surface are equal to the number of magnetic field lines leaving the surface. So the net magnetic flux through any closed surface is zero.
I.e Gauss law for closed surface-
$
\oint \underset{B}{\overrightarrow{d s}} \cdot \overrightarrow{d s}=0
$
Gauss law if the surface is open
$
\int \underset{B}{\vec{B}} \cdot \overrightarrow{d s}=\phi_B
$
i.e Consider an element of the area $d S$ on an arbitrarily shaped surface is shown in the figure. If the magnetic field at this element is $\vec{B}$, the magnetic flux through the element is $d \phi_B=\vec{B} \cdot d \vec{S}=B d S \cos \theta$
So, the total flux through the surface is
$
\phi_B=\int \vec{B} \cdot d \vec{S}=\int B d S \cos \theta
$
Study it with Videos
Magnetism and gauss's law"Stay in the loop. Receive exam news, study resources, and expert advice!"
Get Answer to all your questions
JEE Main Articles
Back to top