Magnetic properties

Question 1

susceptibility when dia

Answer 1

-ve
–1 ≤ χ < 0

Question 2

susceptibility when para

Answer 2

+ve and small
0 < χ < ε

Question 3

susceptibility when ferro

Answer 3

+ve and large
χ&raquo_space; 1

Question 4

Diamagnetic substances

Answer 4

Diamagnetic substances are those which have tendency to move from
stronger to the weaker part of the external magnetic field.

Question 5

Paramagnetic substances

Answer 5

Paramagnetic substances are those which get weakly magnetised when
placed in an external magnetic field. . They have tendency to move from a
region of weak magnetic field to strong magnetic field, i.e., they get weakly
attracted to a magnet.

Question 6

Ferromagnetic substances

Answer 6

Ferromagnetic substances are those which gets strongly magnetised when
placed in an external magnetic field. They have strong tendency to move
from a region of weak magnetic field to strong magnetic field, i.e., they get
strongly attracted to a magnet.

Question 7

explanation for repulsion in diamagnetic substances.

Answer 7

• Electrons in
  an atom orbiting around nucleus possess orbital angular momentum.
  These orbiting electrons are equivalent to current-carrying loop and thus
  possess orbital magnetic moment.
• Diamagnetic substances are the ones
  in which resultant magnetic moment in an atom is zero.
• When magnetic
  field is applied, those electrons having orbital magnetic moment in the
  same direction slow down and those in the opposite direction speed up. This happens due to induced current in accordance with Lenz’s law.
• Thus, the substance develops a net magnetic
  moment in direction opposite to that of the applied field and hence repulsion.

Question 8

The most exotic diamagnetic materials are ______.

Answer 8

superconductors

Question 9

superconductors

Answer 9

These
are metals, cooled to very low temperatures which exhibits both perfect
conductivity and perfect diamagnetism.

Question 10

Meissner effect

Answer 10

. The phenomenon of perfect
diamagnetism in superconductors is called the Meissner effect.

Question 11

Some paramagnetic materials are

Answer 11

aluminium, sodium, calcium,
oxygen (at STP) and copper chloride.

Question 12

factors paramagnetic materials depend on

Answer 12

For a paramagnetic material both χ
and µr
depend not only on the material, but also (in a simple fashion) on
the sample temperature.

Question 13

domain

Answer 13

ferromagnetic substances interact with one another in such a way that they spontaneously align
themselves in a common direction over a macroscopic volume called
domain.

Question 14

Typical domain size

Answer 14

Typical domain size is 1mm

Question 15

the domain contains
about ____ atoms

Answer 15

10 ¹¹

Question 16

hard magnetic materials

Answer 16

ferromagnetic materials the
magnetisation persists.

Question 17

hard magnetic materials examples

Answer 17

Alnico, an alloy of iron, aluminium, nickel, cobalt
and copper, naturally occurring lodestone is
another.

Question 18

soft ferromagnetic materials.

Answer 18

a class of
ferromagnetic materials in which the magnetisation disappears on removal
of the external field. Soft iron is one such material.

Question 19

factors ferromagnetic materials depend on

Answer 19

• temperature.