Magentism And Matter

Question 1

Properties of magnet

Answer 1

Attracts small pieces
Points in N-S direction
Always exists in pairs & no monopole exists
Induces magnetism in a magnetic substance placed near it(induction)

Question 2

Magnetic poles

Answer 2

Regions where magnetic attraction is max

Question 3

Magnetic axis

Answer 3

Line passing through poles of magnet

Question 4

Magnetic equator

Answer 4

Line passing through center of magnet & perp to magnetic axis

Question 5

Magnetic length(2l)

Answer 5

Dist btw 2 poles

Question 6

m=

Answer 6

q(m)2l

Question 7

Unit of m

Answer 7

A m²

Question 8

Q(m) is

Answer 8

Pole strength

Question 9

Bar magnet as equivalent solenoid

Answer 9

B = myu°/4pi 2m/r³

Question 10

Prop of magnetic field lines

Answer 10

Forms continuous loop
Tan to field lines give direction of net B
Dotn intersect

Question 11

Torque on dipole

Answer 11

mBsinø
Stable, unstable, max

Question 12

P.E of magnetic Dipole

Answer 12

Work done is U
U = -mB[cosø2-cosø1]
Max, min, 0

Question 13

Magnestising field

Answer 13

Magnetic field that exist in vacuum and induces magnetism
B°=myu°NI

Question 14

Magnetic field intensity or magnetic intensity

Answer 14

No of ampere turns flowing per unit length
H=nI
H=B°/myu°

Question 15

Intensity of magentisation

Answer 15

Magnetic moment developed per unit volume when placed in M.F
M=m(net)/V
M=q(m)/A Or M=nI(m)

Question 16

Magnetic susceptibility X=

Answer 16

M/H
Ratio of intensity of magnetisation to magnetic field intensity

Question 17

Magnetic permeability

Answer 17

Myu = B/H
Ratio of magnetic induction to magnetic intensity

Question 18

Relative permeability

Answer 18

Myu(r) = myu/myu°

Question 19

Relation btw M,H,khi(m)

Answer 19

B=myuH
H=nI
Khi=m/H

Question 20

Diamagnetic

Answer 20

In uniform B, it is perp to B
In non-uniform B, move from strong to weak region
Expelled by external magnet
Weakly magnetized opp to B
Myu(r) < 1 (small +ve)
Myu < myu°
Weakly concentrated M.F.L
Khi is -ve
Khi(m) is independent of temp
Eg: h20,Cu,Zn,Ld,Gold,Si,NaCl,N, superconductors

Question 21

Paramagnetic

Answer 21

In uniform B, it is || to B
In non-uniform B, move from weak to strong region
Weakly attracted by external magnet
Weakly magnetized || to B
Myu(r) > 1
Myu > myu°
Concentrated M.F.L
Khi is +ve
Khi(m) is inv prop to temp
Eg: manganese, Pt,AL,Chromium,CuCl,O2 ar stp, Na

Question 22

Feromagnetic

Answer 22

In uniform B, it is || to B
In non-uniform B, move from weak to strong region
Strongly attracted by external magnet
Strongly magnetized || to B
Myu(r)&raquo_space; 1
Myu&raquo_space; myu°
Highly concentrated M.F.L
Khi&raquo_space; 1
Khi(m) is dependent on temp
Eg: Lodestone, iron, Ni,Cobalt

Question 23

Meismer effect

Answer 23

Phenomenon when a metal cooled yo a temp below it’s critical temp in B.F it attains both superconductivity & perfect diamagnetism. B gets completely expelled from it & repels a magnet. So Khi is -1 & myu(r) is 0.

Question 24

Hard vs soft feromagnetic substances

Answer 24

Hard retain magnetism even after removal of ext B
Soft dont

Question 25

Soft fero eg

Answer 25

Ni, cobalt, soft iron, temp magnets

Question 26

Hard fero magnet eg:

Answer 26

Alnico,Lodestone, permanent magnet

Question 27

Curie temp

Answer 27

Temp at which fero becomes para

Question 28

In para, susceptibility varies with temperature khi(m) =

Answer 28

C/(T-T(c))