1
MCQ (Single Correct Answer)

JEE Main 2017 (Online) 9th April Morning Slot

A negative test charge is moving near a long straight wire carrying a current. The force acting on the test charge is parallel to the direction of the current. The motion of the charge is :
A
away from the wire
B
towards the wire
C
parallel to the wire along the current
D
parallel to the wire opposite to the current
2
MCQ (Single Correct Answer)

JEE Main 2017 (Online) 9th April Morning Slot

A uniform magnetic field B of 0.3 T is along the positive Z-direction. A rectangular loop (abcd) of sides 10 cm × 5 cm carries a current I of 12 A. Out of the followingdifferent orientations which one corresponds to stable equilibrium ?
A
B
C
D
3
MCQ (Single Correct Answer)

JEE Main 2018 (Offline)

An electron, a proton and an alpha particle having the same kinetic energy are moving in circular orbits of radii re, rp, r$$_\alpha$$ respectively in a uniform magnetic field B. The relation between re, rp, r$$_\alpha$$ is:
A
re < r$$_\alpha$$ < rp
B
re > rp = r$$_\alpha$$
C
re < rp = r$$_\alpha$$
D
re < rp < r$$_\alpha$$

Explanation

When a charged particle moves in a magnetic field then the charged particle moves in a circular path. So,

$${{m{v^2}} \over r}$$ = Bqv

$$ \Rightarrow $$$$\,\,\,$$ r = $${{mv} \over {Bq}}$$

We know kinetic energy, K = $${1 \over 2}$$ mv2

$$\therefore\,\,\,$$ mv = $$\sqrt {2Km} $$

$$\therefore\,\,\,$$ r = $${{\sqrt {2Km} } \over {Bq}}$$

According to the question,

Ke (electron) = Kp (proton) = K$$\alpha $$(Alpha particle) = K = constant, and all of them are in uniform magnetic field.

$$ \therefore $$ B = constant.

$$\therefore\,\,\,$$ r $$ \propto $$ $${{\sqrt m } \over q}$$

For proton (1H1), mass = m, and charge = e

$$\therefore\,\,\,$$ rp $$ \propto $$ $${{\sqrt m } \over e}$$

For alpha particle (2H4),

mass = 4m

and charge = 2e

$$\therefore\,\,\,$$ r$$ \alpha $$ $$ \propto $$ $${{\sqrt {4m} } \over {2e}}$$ $$ \propto $$ $${{\sqrt m } \over e}$$

$$ \therefore $$$$\,\,\,$$ rp = r$$ \alpha$$

For electron,

charge = e

and mass (me) = 9.1 $$ \times $$ 10$$-$$31 kg

and mass of proton = 1.67 $$ \times $$ 10$$-$$27 kg

$$\therefore\,\,\,$$ mass of electron < mass of proton.

re $$ \propto $$ $${{\sqrt {{m_e}} } \over e}$$ < rp

$$\therefore\,\,\,$$ re < rp = r$$ \propto $$
4
MCQ (Single Correct Answer)

JEE Main 2018 (Offline)

The dipole moment of a circular loop carrying a current I, is m and the magnetic field at the centre of the loop is B1. When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is $${{B_2}}$$. The ratio $${{{B_1}} \over {{B_2}}}$$ is:
A
2
B
$$\sqrt 3 $$
C
$$\sqrt 2 $$
D
$$1 \over \sqrt 2 $$

Explanation

Dipole moment, M = IA

Let radius of circular loop = R

$$\therefore\,\,\,$$ M  =  I $$ \times $$ $$\pi $$R2

Later, we keep current constant ,

But dipole moment becomes double, let new radius = R1

$$\therefore\,\,\,$$ 2M  =  I $$ \times $$ $$\pi $$R$$_1^2$$

$$ \Rightarrow $$$$\,\,\,$$ 2I$$\pi $$R2  =  I$$\pi $$R$$_1^2$$

$$ \Rightarrow $$$$\,\,\,$$ R1  =  $$\sqrt 2 $$ R

At the center of circular ring, the magnetic field,

B  =  $${{{\mu _0}I} \over {2R}}$$

$$\therefore\,\,\,$$ B1  =  $${{{\mu _0}I} \over {2R}}$$   and    B2 = $${{{\mu _0}I} \over {2 \times \left( {\sqrt 2 R} \right)}}$$

$$\therefore\,\,\,$$ $${{{B_1}} \over {{B_2}}}$$  =   $${{{{{\mu _0}I} \over {2R}}} \over {{{{\mu _0}I} \over {2\sqrt 2 \,R}}}}$$

= $${{2\sqrt 2 } \over 2}$$

= $$ \sqrt 2 $$

Questions Asked from Magnetics

On those following papers in MCQ (Single Correct Answer)
Number in Brackets after Paper Name Indicates No of Questions
AIEEE 2002 (4)
keyboard_arrow_right
AIEEE 2003 (5)
keyboard_arrow_right
AIEEE 2004 (7)
keyboard_arrow_right
AIEEE 2005 (5)
keyboard_arrow_right
AIEEE 2006 (3)
keyboard_arrow_right
AIEEE 2007 (5)
keyboard_arrow_right
AIEEE 2008 (2)
keyboard_arrow_right
AIEEE 2009 (2)
keyboard_arrow_right
AIEEE 2010 (1)
keyboard_arrow_right
AIEEE 2011 (1)
keyboard_arrow_right
AIEEE 2012 (2)
keyboard_arrow_right
JEE Main 2013 (Offline) (1)
keyboard_arrow_right
JEE Main 2014 (Offline) (2)
keyboard_arrow_right
JEE Main 2015 (Offline) (2)
keyboard_arrow_right
JEE Main 2016 (Offline) (3)
keyboard_arrow_right
JEE Main 2016 (Online) 9th April Morning Slot (3)
keyboard_arrow_right
JEE Main 2016 (Online) 10th April Morning Slot (3)
keyboard_arrow_right
JEE Main 2017 (Offline) (2)
keyboard_arrow_right
JEE Main 2017 (Online) 8th April Morning Slot (3)
keyboard_arrow_right
JEE Main 2017 (Online) 9th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2018 (Offline) (2)
keyboard_arrow_right
JEE Main 2018 (Online) 15th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2018 (Online) 15th April Evening Slot (1)
keyboard_arrow_right
JEE Main 2018 (Online) 16th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 9th January Morning Slot (5)
keyboard_arrow_right
JEE Main 2019 (Online) 9th January Evening Slot (3)
keyboard_arrow_right
JEE Main 2019 (Online) 10th January Morning Slot (3)
keyboard_arrow_right
JEE Main 2019 (Online) 10th January Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 11th January Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 11th January Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 12th January Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 12th January Evening Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 8th April Morning Slot (3)
keyboard_arrow_right
JEE Main 2019 (Online) 8th April Evening Slot (3)
keyboard_arrow_right
JEE Main 2019 (Online) 9th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 9th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 10th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 10th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 12th April Morning Slot (4)
keyboard_arrow_right
JEE Main 2019 (Online) 12th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 7th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 7th January Evening Slot (4)
keyboard_arrow_right
JEE Main 2020 (Online) 8th January Morning Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 8th January Evening Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 9th January Morning Slot (3)
keyboard_arrow_right
JEE Main 2020 (Online) 9th January Evening Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 4th September Morning Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 2nd September Morning Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 2nd September Evening Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 3rd September Morning Slot (3)
keyboard_arrow_right
JEE Main 2020 (Online) 3rd September Evening Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 4th September Evening Slot (3)
keyboard_arrow_right
JEE Main 2020 (Online) 5th September Morning Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 5th September Evening Slot (4)
keyboard_arrow_right
JEE Main 2020 (Online) 6th September Morning Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 6th September Evening Slot (3)
keyboard_arrow_right
JEE Main 2021 (Online) 24th February Evening Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 25th February Morning Slot (2)
keyboard_arrow_right
JEE Main 2021 (Online) 25th February Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 26th February Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 16th March Morning Shift (4)
keyboard_arrow_right
JEE Main 2021 (Online) 16th March Evening Shift (2)
keyboard_arrow_right
JEE Main 2021 (Online) 17th March Morning Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 17th March Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 18th March Morning Shift (3)
keyboard_arrow_right
JEE Main 2021 (Online) 18th March Evening Shift (2)
keyboard_arrow_right
JEE Main 2021 (Online) 20th July Morning Shift (2)
keyboard_arrow_right
JEE Main 2021 (Online) 20th July Evening Shift (3)
keyboard_arrow_right
JEE Main 2021 (Online) 22th July Evening Shift (3)
keyboard_arrow_right
JEE Main 2021 (Online) 25th July Morning Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 25th July Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 27th July Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 26th August Morning Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 26th August Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 27th August Morning Shift (2)
keyboard_arrow_right
JEE Main 2021 (Online) 27th August Evening Shift (2)
keyboard_arrow_right
JEE Main 2021 (Online) 31st August Morning Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 31st August Evening Shift (3)
keyboard_arrow_right

EXAM MAP

Joint Entrance Examination

JEE Advanced JEE Main

Graduate Aptitude Test in Engineering

GATE CSE GATE ECE GATE ME GATE PI GATE EE GATE CE GATE IN

Medical

NEET