JEE Main Last 10 Years Question Papers with Solutions PDF 2024 to 2014

# Magnetic Flux - Practice Questions & MCQ

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #JEE Main

## Quick Facts

• Magnetic flux is considered one of the most asked concept.

• 19 Questions around this concept.

## Solve by difficulty

A square loop of side 4 cm is lying on a horizontal table. A uniform magnetic field of 0.5 T is directed towards at an angle of 60° to the vertical as shown in figure. If the field
increases from zero to its final value in 0.2s, the e.m.f. induced in the loop will be

A small loop of the area of the cross section $10^{-4} \mathrm{~m}^2$ is lying concentrically and coplanar inside a bigger loop of radius 0.628 m. A current of 10 A is passed in the bigger loop. The smaller loop is rotated about its diameter with an angular velocity $\omega$. The magnetic flux linked with the small loop will be :

A series combination of an inductance (L) and a resistance (R) is connected to a battery of emf E. The final value of current depends on

Two concentric coplanar circular loops 1 and 2 are shown in the Fig 19. The radii of the loops are r and R. Current I flows in the loop
1. Find the magnetic flux $\Phi_2$ through the loop 2 if r << R

Two coils A and B are separated by a certain distance. If a current of 4 A flows through A, a magnetic flux of $\mathrm{10^{-3}}$ Wb passes through B (no current through B). If no current passes through A and a current of 2A passes through B, then the flux through A is:

The magnetic flux linked with a coil of N turns of area of cross-section A held with its plane parallel to the field B is:

A circular disc of radius 0.2 m is placed in a uniform magnetic field of induction $\mathrm {\mathrm{n}\left(\frac{1}{\pi}\right)Wbm^{-2}}$ in such a way that its axis makes an angle of 60° with B. The magnetic flux linked with the disc is:

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A uniform but time varying magnetic field is present in a circular region of radius R. The magnetic field is perpendicular and into the plane of the loop and the magnitude of field is increasing at a constant rate $\mathrm{\alpha }$ . There is a straight conducting rod of length 2R placed as shown in figure. The magnitude of induced emf across the rod is:

## Concepts Covered - 1

Magnetic flux

Magnetic flux-

The total number of magnetic lines of force passing normally through an area placed in a magnetic field is equal to
the magnetic flux linked with that area.

I.e for the below figure

Net magnetic flux through the surface is given by

$\phi_B = \oint \vec{B}\cdot \vec{dA}= BA\cos \Theta$

where

$\phi_B=$ Magnetic Flux

$B =$ Magnetic field

$\Theta =$ The angle between area vector and magnetic field vector

• Magnetic flux is a scalar quantity.
• Unit of magnetic flux -

It's S.I. unit is Weber (wb) or $Tesla\times m^2$ and its C.G.S. unit is maxwell(Mx).

and $1 \ w b=1 \ T m^{2}$  and $1 \ Mx = 10^{-8 } \ wb$

• The dimension of magnetic flux is $ML^{2}T^{-2}A^{-1}$
• if θ = 0 then $\phi = BA$ and  Flux will be positive.
• If  $\theta =\frac{\pi }{2}$ then Flux will be zero (i.e $\phi = 0$)

## Study it with Videos

Magnetic flux

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