31 Year NEET Previous Year Questions: Magnetism & Matter - NEET MCQ

# 31 Year NEET Previous Year Questions: Magnetism & Matter - NEET MCQ

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## 26 Questions MCQ Test Physics Class 12 - 31 Year NEET Previous Year Questions: Magnetism & Matter

31 Year NEET Previous Year Questions: Magnetism & Matter for NEET 2024 is part of Physics Class 12 preparation. The 31 Year NEET Previous Year Questions: Magnetism & Matter questions and answers have been prepared according to the NEET exam syllabus.The 31 Year NEET Previous Year Questions: Magnetism & Matter MCQs are made for NEET 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for 31 Year NEET Previous Year Questions: Magnetism & Matter below.
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31 Year NEET Previous Year Questions: Magnetism & Matter - Question 1

### A bar magnet is oscillating in the earth’s magneticfield with a period T. What happens to its periodof motion, if its mass is quadrupled [1994, 03]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 1

The time period of a bar magnet in a magnetic field is given by.

Here, I = moment of inertia ∝ m , M = moment of magnet, B = magnetic field.

, so, T becomes twice as mass becomes four times

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 2

### The work done in turning a magnet of magneticmoment M by an angle of 90° from the meridian,is n times the corresponding work done to turnit through an angle of 60°. The value of n isgiven by      [1995]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 2

Magnetic moment = M; Initial angle through which magnet is turned (θ1) = 90º and final angle through which magnet is turned (θ2)= 60º.
Work done in turning the magnet
through 90º(W1) = MB (cos 0º – cos  0º)
= MB (1–0) = MB.
Similarly, W2 = MB (cos 0º – cos 60º)

∴ W1 = 2W2 or n = 2.

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31 Year NEET Previous Year Questions: Magnetism & Matter - Question 3

### For protecting a sensitive equipment from theexternal electric arc, it should be [1998]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 3

The iron can produces a magnetic screening for the equipment as lines of magnetic force can not enter iron enclosure.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 4

If a diamagnetic substance is brought near northor south pole of a bar magnet, it is [1999]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 4

Diamagnetic substances do not have any unpaired electron. And they are magnetised in direction opposite to that of magnetic field.
Hence, when they are brought to north or south pole of a bar magnet, they are repelled by poles.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 5

A bar magnet, of magnetic moment  , is placed in a magnetic field of induction  . The torque exerted on it is

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 5

We know that when a bar magnet is placed in the magnetic field at an angle θ, then torque acting on the bar magnet (τ)

Note : This torque τ has a tendency to make the axis of the magnet parallel to the direction of the magnetic field.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 6

Current i is flowing in a coil of area A and number of turns N, then magnetic moment of the coil, M
is         [2001]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 6

Magnetic moment linked with one turn = iA Magnetic moment linked with N turns
= iNA amp-m2. Here, A = Area of current loop.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 7

Two magnets of magnetic moments M and 2M  are placed in a vibration magnetometer, with theidentical poles in the same direction. The timeperiod of vibration is T1. If the magnets areplaced with opposite poles together and vibratewith time period T2, then           [2002]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 7

Obviously, T2 > T1

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 8

A diamagnetic material in a magnetic field moves

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 8

A diamagnetic material in a magnetic field moves from stronger to the weaker parts of the field.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 9

According to Curie’s law, the magnetic susceptibilityof a substance at an absolutetemperature T is proportional to [2003]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 9

According to Curie’s law

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 10

A coil in the shape of an equilateral triangle of side l is suspended between the pole pieces of a  permanent magnet such that  is in the plane of the coil. If due to a current i in the triangle a torque τ acts on it, the side l of the triangle is      [2005]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 10

τ = MB sinθ
τ = iAB sin90º

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 11

If the magnetic dipole moment of an atom ofdiamagnetic material, paramagnetic material andferromagnetic material are denoted by μd, μp andμf respectively, then [2005]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 11

The magnetic dipole moment of diamagnetic material is zero as each of its pair of electrons
have opposite spins, i.e., μd = 0.
Paramagnetic substances have dipole
moment > 0, i.e. μp ≠ 0, because of excess of electrons in its molecules spinning in the same direction.
Ferro-magnetic substances are very strong magnets and they also have permanent magnetic moment, i.e. μf ≠ 0.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 12

Above Curie temperature       [2006]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 12

Above Curie Temperature, a ferromagnetic substance becomes paramagnetic

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 13

Nickel shows ferromagnetic property at roomtemperature. If the temperature is increasedbeyond Curie temperature, then it will show                [2007]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 13

Beyond Curie temperature, ferromagnetic substances behaves like a paramagnetic substance.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 14

Curie temperature is the temperature abovewhich         [2008]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 14

Curie temperature is the temperature above which ferromagnetic material becomes paramagnetic material.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 15

A bar magnet having a magnetic moment of 2× 104 JT–1 is free to rotate in a horizontal plane.A horizontal magnetic field B = 6 × 10–4 T existsin the space. The work done in taking the magnetslowly from a direction parallel to the field to a direction 60° from the field is           [2009]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 15

Work done
= MB (cos θ1 – cos θ2)
= MB (cos 0° – cos 60°)

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 16

If a diamagnetic substance is brought nearthe north or the south pole of a bar magnet, itis: [2009]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 16

Diamagnetic substances are repelled by
external magnetic fields.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 17

A vibration magnetometer placed in magneticmeridian has a small bar magnet. The magnetexecutes oscillations with a time period of 2 secin earth's horizontal magnetic field of 24 microtesla. When a horizontal field of 18microtesla is produced opposite to the earth'sfield by placing a current carrying wire, the newtime period of magnet will be       [2010]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 17

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 18

Electromagnets are made of soft iron because soft iron has     [2010]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 18

Solution :-Soft iron is a soft magnetic material. Hence, Electromagnetics are made of soft iron because soft iron has low retentivity and low coercive force or low coercivity.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 19

Two identical bar magnets are fixed with their centres at a distance d apart. A stationary charge Q is placed at P in between the gap of the two magnets at a distance D from the centre O as shown in the Figure

The force on the charge Q is

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 19

Force on a charged particle is given by F = qvB. Here v = 0 and also resultant B is zero.
∴ Force = 0

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 20

The magnetic moment of a diamagnetic atom is

[2010]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 20

The magnetic moment of a diamagnetic
atom is equal to zero.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 21

There are four light–weight–rod samples A,B,C,D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted              [2011]
(i) A is feebly repelled
(ii) B is feebly attracted
(iii) C is strongly attracted
(iv) D remains unaffected

Which one of the following is true ?

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 21

A → diamagnetic
B → paramagnetic
C → Ferromagnetic
D → Non magnetic

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 22

A short bar magnet of magnetic moment 0.4J T–1 is placed in a uniform magnetic field of 0.16 T. Themagnet is in stable equilibrium when the potentialenergy is [2011M]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 22

For stable equilibrium
U = –MB
= – (0.4) (0.16)
= – 0.064 J

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 23

A compass needle which is allowed to move in ahorizontal plane is taken to a geomagnetic pole.It : [2012]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 23

Since magnetic field is in vertical direction and needle is free to totate in horizontal plane only so magnetic force cannot rotate the needle in horizontal plane so needle can stay in any position.

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 24

A magnetic needle suspended parallel to a magnetic field requires √3 J of work to turn it through 60°. The torque needed to maintain the needle in this position will be : [2012M]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 24

According to work energy theorem

From equation (i) and (ii)

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 25

A bar magnet of length ‘ℓ’ and magnetic dipole moment ‘M’ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be                 [NEET 2013]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 25

Magnetic dipole moment
M = m × ℓ         M' = m × r
From figure

31 Year NEET Previous Year Questions: Magnetism & Matter - Question 26

A bar magnet of magnetic moment M is placed atright angles to a magnetic induction B. If a force F is experienced by each pole of the magnet, thelength of the magnet will be          [NEET Kar. 2013]

Detailed Solution for 31 Year NEET Previous Year Questions: Magnetism & Matter - Question 26

FL = MB (= Torque) ⇒L = MB/F

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