magnetism and matter

Question 1

Write the properties of Magnetic Field Lines

Answer 1

▪ The magnetic field lines of a magnet form continuous closed loops.
▪ The tangent to the field line at a given point represents the direction
of the net magnetic field B at that point.
▪ The larger the number of field lines crossing per unit area, the
stronger is the magnitude of the magnetic field B.
▪ The magnetic field lines do not intersect.

Question 2

Torque in an external field

Answer 2

t = m × B

Question 3

Energy in an external field

Answer 3

U = −m . B

Question 4

Define magnetic flux

Answer 4

Magnetic flux is defined as the number of magnetic field lines passing through a given closed surface.

The SI unit of magnetic flux is weber (Wb) or tesla meter squared (T m2 )

Question 5

SI unit of magnetic flux?

Answer 5

weber

Question 6

Why does Gauss’s Law in magnetism give a null result

Answer 6

Gauss’s Law in magnetism give a null result as isolated magnetic
poles(monopole) do not exist

Question 7

Define Magnetisation(M).

Answer 7

The net magnetic dipole moment developed per unit volume of a material
is called Magnetisation

Question 8

. Define Magnetic Susceptibility

Answer 8

The measure of how much a material will be magnetized in an applied magnetic field.

Question 9

properties of dia

Answer 9

weakly magnetized in the opp direction of
external magnetic field

they move from stronger to weaker part of the magnetic field

magnetic susceptibility is negative

They have a relative permeability of less than 1.

no field lines inside the material

Question 10

properties of para

Answer 10

weakly magnetized in the direction of
external magnetic field

they move from weaker to stronger part of the magnetic field

magnetic susceptibility is positive and small

They have a relative permeability of more than 1

field lines are concentrated inside the material

Question 11

properties of ferro

Answer 11

strongly magnetized in the direction of
external magnetic field

they move from weaker to stronger part of the magnetic field

magnetic susceptibility is positive and large

They have a relative permeability wayyyy more than 1

field lines are highly concentrated inside the material

Question 12

examples of diamagnetism

Answer 12

Water ,Lead , Carbon (diamond and graphite),Bismuth ,Silver, Mercury, Copper, Neon, Pyrolytic ,carbon

Question 13

examples of ferro

Answer 13

iron , cobalt, nickle

Question 14

example’s of para

Answer 14

aluminium ,sodium, calcium

Question 15

.How will you classify magnetic materials in terms of their susceptibility.

Answer 15

Diamagnetic - χ is negative. χ < 0
Paramagnetic - χ is positive and small, χ > 0
Ferromagnetic - χ is large and positive, χ&raquo_space; 1

Question 16

How will you classify magnetic materials in terms of their relative
permeability.

Answer 16

Diamagnetic - μr< 1
Paramagnetic - μr> 1
Ferromagnetic - μr» 1

Question 17

Write two examples each for diamagnetic, paramagnetic and
ferromagnetic materials.

Answer 17

Diamagnetic- water , sodium chloride, diamond, gold.
Paramagnetic - aluminium, sodium, calcium, magnesium, platinum,
tungsten
Ferromagnetic - iron, cobalt, nickel, gadolinium,Fe2O3

Question 18

.Mention the behaviour of a dia and ferromagnetic materials when they
are placed in a non uniform magnetic field.

Answer 18

▪ Diamagnetic substances move from stronger to the weaker part of the
external magnetic field.
▪ Ferromagnetic substances move from weaker to stronger part of the
external magnetic field

Question 19

What are super conductors

Answer 19

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