Consider the following statements regarding magnetic materials: 1. A diamagnetic material has no permanent dipole 2. Paramagnetic material has anti parallel orientation of equal moments with neighbouring dipoles 3. Ferrimagentic material has anti parallel orientation of unequal moments between neighbouring diploes Which of these statements are correct?

Consider the following statements: 1. Both ferromagnetic and ferrimagnetic materials have domain structures; each domain has randomly oriented magnetic moments when no external field is applied. 2. Both ferromagnetic and ferrimagnetic materials make those domains that have a favourable orientation to the applied field grow in size. 3. The net magnetic moment in ferromagnetic materials is higher than that in ferrimagnetic materials. 4. The net magnetic moment in ferrimagnetic materials is higher than that in ferromagnetic material. Which of the above statements are correct?

A

1 and 4 only

B

1, 2 and 4

C

2 and 4 only

D

1, 2 and 3

Which of the following statements are true regarding diamagnetic substances? (i) Diamagnetic substances are feebly repelled by magnets (ii) Diamagnetic substances move from stronger field side to weaker field side (iii) Permeability of diamagnetic substances is greater than one. (µ > 1)

A

All are true

B

Only (i) is true

C

Only (i) and (ii) are true

D

Only (ii) and (iii) is true

Ferrimagnetic materials have anti parallel orientation of equal moments of permanent dipoles.

A

True

B

False

Among the following properties describing diamagnetism identify the property that is wrongly stated a) diamagnetic material do not have permanent magnetic moment. b) diamagnetism is explained in terms of electromagnetic induction c) diamagnetic materials have a small positive susceptibility d) the magnetic moment of individual electrons neutralise each other

A

a

B

b

C

c

D

d

A magnetic dipole of dipole moment $$\overrightarrow {\bf{m}} $$ is placed in a non-uniform magnetic field $$\overrightarrow {\bf{B}} .$$ If the position vector of the dipole is $$\overrightarrow {\bf{r}} ,$$ the torque acting on the dipole about the origin is

A

$$\overrightarrow {\bf{r}} \times \left( {\overrightarrow {\bf{m}} \times \overrightarrow {\bf{B}} } \right)$$

B

$$\overrightarrow {\bf{r}} \times \overrightarrow \nabla \left( {\overrightarrow {\bf{m}} .\overrightarrow {\bf{B}} } \right)$$

C

$$\overrightarrow {\bf{m}} \times \overrightarrow {\bf{B}} $$

D

$$\overrightarrow {\bf{m}} \times \overrightarrow {\bf{B}} + \overrightarrow {\bf{r}} \times \overrightarrow \nabla \left( {\overrightarrow {\bf{m}} .\overrightarrow {\bf{B}} } \right)$$

Consider the following statements regarding hysteresis loops of hard and soft magnetic materials: 1. Hysteresis loss of hard magnetic material will be less than that of soft material 2. Coercivity of hard material will be greater than that of soft material 3. Retentivity of the two materials will always be equal Which of these statements are correct?

A

1, 2 and 3

B

2 only

C

3 only

D

1 and 3 only

Continuous flue gas analyser makes use of paramagnetic properties of some of its constituents, which move towards the strongest part of the magnetic field thus displacing diamagnetic gases. Which of the following gases is diamagnetic?

A

CO₂

B

O₂

C

NO

D

NO₂

Which of the following is a magnetic material in which a permanent atomic magnetic dipole has a parallel orientation?

A

Ferromagnetic

B

Diamagnetic

C

Paramagnetic

D

Ferrimagnetic

Which of the following types of inter molecular interactions or forces is/are called van der Waals forces? 1. London forces 2. Dipole - dipole forces 3. Dipole - induced dipole forces 4. Hydrogen bonding Choose the correct code:

A

Only 2, 3 and 4

B

Only 1, 2 and 3

C

Only 3 and 4

D

Only 1 and 2

Two magnetic dipoles of magnitude m each are placed in a plane as shown below. The energy of interaction is given by
Electromagnetic Theory mcq question image

Electromagnetic Theory mcq question image

A

zero

B

$$\frac{{{\mu _0}}}{{4\pi }} \cdot \frac{{{m^2}}}{{{d^3}}}$$

C

$$\frac{{3{\mu _0}}}{{2\pi }} \cdot \frac{{{m^2}}}{{{d^3}}}$$

D

$$ - \frac{{3{\mu _0}}}{{8\pi }} \cdot \frac{{{m^2}}}{{{d^3}}}$$

Classification	Permanent dipoles	Interaction between neighboring dipoles
Diamagnetic	No	-
Paramagnetic	Yes	Zero or Negligible
Ferromagnetic	Yes	Parallel orientation
Antiferromagnetic	Yes	The antiparallel orientation of equal moments
Ferrimagnetic	Yes	The antiparallel orientation of unequal moments

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