1.

Which one of the following has negative value of susceptibility?

(a) Nickel (b) Aluminium (c) Lead (d) Iron

2.

Which one of the following has relative magnetic permeability between 0 and 1?

(a) Aluminium (b) Alnico (c) Water (d) Sodium

3.

Which of the following has its permeability less than that of free space?

(a) Copper (b) Aluminium (c) Copper chloride (d) Nickel

4.

A diamagnetic substance is brought near the north or south pole of a bar magnet. It will be :

(a) repelled by both the poles.

(b) attracted by both the poles.

(c) repelled by the north pole and attracted by the south pole.

(d) attracted by the north pole and repelled by the south pole.

1.

A wire of length L is bent round in the form of (i) a square, and then (ii) an equilateral triangle. 

If current I is passed through each of them, find the ratio of magnetic moment of the square loop to that of the triangle.

(CBSE 2023, 2M)

2.

(a) Derive the expression for the torque acting on a current carrying loop placed in a magnetic field.

(b) Explain the significance of a radial magnetic field when a current carrying coil is kept in it.

(CBSE 2019, 3M)

3.

A proton is accelerated through a potential difference V, subjected to a uniform magnetic field acting normal to the velocity of the proton. If the potential difference is doubled, how will the radius of the circular path described by the proton in the magnetic field change?

(CBSE 2019, 2M)

4.

Write one important property of a paramagnetic material.

(CBSE 2019, 5M)

Chapter Name

Sub Topics of Chapter 5: Magnetism and Matter

Magnetism and Matter

5.1 Introduction

5.2 The Bar Magnet

5.3 Magnetic Field Lines

5.4 Earth’s Magnetism

5.5 Magnetic Declination and Inclination

5.6 Magnetic Properties of Materials

5.7 Diamagnetism, Paramagnetism, and Ferromagnetism

5.8 Hysteresis

5.9 Magnetic Permeability and Susceptibility

5.10 Applications of Magnetism in Daily Life

New Q.

key

Explanations

1.

B

The magnetic susceptibility is negative for diamagnetic materials <Lead is example>

2.

C

For diamagnetic materials the relative magnetic permeability lies b/w 0 and 1 e.g. water.

3.

B

Aluminum permeability is less than that of free space.

4.

A

Diamagnetic materials create an induced magnetic field in a direction opposite to an externally applied magnetic field. Hence repelled by both the poles.

5.

D

Copper is diamagnetic material and repels magnetic field slightly.

6.

C

Diamagnetic materials exhibit magnetism but the reason is incorrect ∵ the diamagnetic materials generate weak repulsion in an external magnetic field due to induced magnetic fields, not necessarily because of permanent magnetic dipole moments.

7.

A

Copper [ferromagnetic] 

8.

C

Sodium Chloride

9.

B

M = I ∙ A

1 × 𝜋r2 

2𝜋r = 4.4

= 7.7 × 0.2

= 1.54 Am2

10.

C

= 1 × 3.14 × 10–2  × 10–3 

= 31.4 𝜇Wb

11.

B

= 0.29 ≅ 0.3MB

12.

A

small and negative

13.

D

Nickel and Cobalt

14.

A

15.

A

W = Uf - Uin

Uin = -MB Cos 0° = -MB

Uf = -MB Cos 180° = MB

⇒ w = -2MB

W = -2 × 3 × 0.2 = -1.2 Joulse

16.

B

M = IA

M = 1 Ampere × πR2   --(1)

2πR = 4

Put in (1)

Correction in option c or d (correction not mentioned)

17.

A

M = NIA

= 10 × 6.4 × π × 0.01

= 2.01 Am2

18.

C

Q = 0°

U = -MB [min potential energy]

19.

B

In a dipole, net magnetic charge is zero

⇒ No net flux across any closed surface

20.

B

Magnetic field lines are closed loops

⇒As many lines enter the Gaussian surface as they leave.

⇒ Net flux is zero and net enclosed magnetic charge is zero

⇒ magnetic charge always occur in dipoles.

21.

B

Where qm is the magnetic charge (monopole) enclosed by the surface.

22.

B

Conceptual.

23.

C

High resistivity and high coerceivity  ie ability to retain magnetic field ^ resistance to demagnetization.

24.

C

Xm is independent of temperature. So -0.05 [Diamagnetic materials]

25.

C

Formula Direct

26.

D

Bo = Vo, B = , B = √2 BO

27.

B

Diamagnetic [Theory based]

28.

A

Susceptibility will decrease by factor of

So %age change in magnetic susceptibility is  (0.833-1) × 100% = -16.7%

So the magnetic susceptibility decreases by 16.7%

29.

D

Conceptual / Theoretical

30.

C

The material with maximum susceptibility is easy to magnetised. 

Hence A is the material which is easiest to magnetise.

31.

C

Conceptual

32.

C

Above the critical temp, they may exhibit normal diamagnetic behavior and below their critical temp they show the properties of super conductors perfect diamagnetism.

33.

B

High permeability, low retentivity, low coerceivity and high saturation point.

34.

C

factual

35.

B

High magnetic permeability to easy magnetic flux flone.

Low hysteresis losses to minimize energy work.

36.

A

X = 1 [shows material is diamagnetic]

μr = 0 [material expels magnetic fields and does not allow them to penetrate]

37.

B

For perfect diamagnetism, susceptibility

χ = –1 and μr = 1 + χ

38.

A

Super conductors shows perfect diamagnetism below critical temperature.

39.

A

Conceptual