In this slide show I have explained how magnetic dipole moment is formed and classification of different magnetic materials. I have also explained how B-H curve is plotted, I explained why B-H Curve is also called as Hysteresis loss.

1. ELECTRICAL
ENGINEERING
by - Mohammed Waris Senan

2. Mohammed Waris Senan 2
MAGNETIC MATERIALS
&
B-H CURVE

3. Content
Magnetic Dipole and Dipole Moment
Magnetic Materials and their properties
Magnetic Domain (Domain Theory)
B-H Curve or Hysteresis Loop
Hysteresis Loss
Mohammed Waris Senan 3

4. Mohammed Waris Senan 4
Magnetic Dipole Moment
+
e
NS
S N
S
DIPOLE
Dipole Moment, M = NIA
Direction of Dipole Moment is from S-Pole to N-Pole
Every substance has Magnetic Dipole Moment

5. Mohammed Waris Senan 5
Magnetic Materials
 Every substance contains magnetic dipole.
 The dipoles are arranged in random orientations.
 Due to random orientation some materials cancel out the dipole moments and some posses resultant dipole
moment.
 When Magnetic field is applied, dipoles try to align themselves in the direction of applied magnetic field.
NS
)B(H

or
H

MR= 0≠

6. Mohammed Waris Senan 6
Magnetic Materials contd..
 Paramagnetic Materials
 Gets weakly magnetise in the direction of applied magnetic field i.e. weakly attracted by the magnet.
 Examples: Aluminium, Manganese, Platinum etc.
 Diamagnetic Materials
 Gets weakly magnetise in opposite direction of applied magnetic field i.e. weakly repelled by the magnet.
 Examples: Copper, Phosphorous, Antimony etc.
 Ferromagnetic Materials
 Gets strongly magnetise in the direction of applied magnetic field i.e. strongly attracted by the magnet.
 Examples: Iron, Nickel, Cobalt & their alloys.
 Antiferromagnetic Materials
 Gets strongly magnetise in the opposite direction of applied magnetic field i.e. strongly repelled by the
magnet.
 Examples: Chromium, Nickel Oxide (NiO), Chromium Oxide (Cr2O3) etc.
 Ferrimagnetic Materials
 Very similar to Ferromagnetic materials but Gets not that strongly magnetise in the direction of applied
magnetic field as a Ferromagnetic material
 Examples: Ferrites like barium ferrite, magnetite etc.

7. Mohammed Waris Senan 7
Magnetic Domain
H

MR= 0≠
Magnetic
Domain
 Magnetic Domain:
Group of dipoles arranged in a particular direction
 Spontaneous Magnetization (Msp):
Resultant dipole moment present when no external
magnetic field is applied.
 Magnetic Susceptibility (χm):
Quantitative measure of the extent to which a material may
be magnetized in relation to a given applied magnetic field.
Mathematically, χm=
𝑀𝑎𝑔𝑛𝑒𝑡𝑖𝑧𝑎𝑡𝑖𝑜𝑛 (𝑀)
𝑀𝑎𝑔𝑛𝑒𝑡𝑖𝑐 𝐹𝑖𝑒𝑙𝑑 𝑆𝑡𝑟𝑒𝑛𝑔𝑡ℎ (𝐻)

8. Mohammed Waris Senan 8
B-H Curve
abe
NS
a b
i
l
Ni
H  iH 
A

B B 

9. Mohammed Waris Senan 9
B-H Curve contd..
i
t
)( B
)( iH 
Im
- Im
- Im Im
Retentivity (Br)
Coercivity (Hc)

10. Mohammed Waris Senan 10
B-H Curve contd..
)( B
)( iH 
- Im Im
H = 0
&
B ≠ 0
H ≠ 0
&
B = 0
 B becomes ZERO after H i.e. B lags H or B
hysteresis H.
 B-H curve is also called as HYSTERESIS
LOOP.
H
i
t
Hysteresis Loss
Hysteresis Loss is proportional to the area of loop
P
Q