RAI SAHEB BHANWAR SINGH COLLEGE NASRULLAGANJ

1. PHYSICS PRESENTATION
SUBMITTED BY-GROUP ‘B’
GROUP MEMBERS-DIVYA
YADAV,KHUSHBU SONI,DEEPIKA
JAT,RUCHITA SOLANKI,NIDHI
PARASHAR.
CLASS- B.SC (CS) 4TH
SEMESTER

2. TOPIC
MAGNETOSTATICS

3. SUBMITTED TO-
MR. GYANRAO DHOTE SIR

4. CONTENTS
1.INTRODUCTION
2.APPLICATION
3.RE-INTRODUCING FARADAY’S
LAW
4.CURRENT SOURCES
5.MAGNETIZATION

5. 1.INTRODUCTION
Magnetostatics is the study of magnetic
fields in systems where the currents are
steady(not changing with time).It is the
magnetic analogue of
electrostatics,where the charges are
stationary.The magnetization need not
be static.

7. Magnetostatics is even a good
approximation when the currents are
not static-as long as the currents do not
alternate rapidly.Magnetostatics is
widely used in applications of
micromagnetics such as models of
magnetic recording devices.

9. 2.APPLICATIONS
Magnetostatics as a special case of
Maxwell’s equations.
Starting from Maxwell’s equations and
assuming that charges are either fixed
or move as a steady current ‘J’,the
equations separate into two equations
for the electric field(see
electrostatics)and two for the magnetic
field.

11. The quality of this approximation may be
guessed by comparing the above
equations with the full version of Maxwell’s
equation and considering the importance
of the terms that have been removed.If the
‘J’ term is substantially larger,then the
smaller term may be ignored without
significant loss of accuracy.

13. 3.RE-INTRODUCING FARADAY’S LAW
A common technique is solve a series of
magnetostatics problems at incremental
time steps and then use these solutions
to approximate the term.Plugging this
result into Faraday’s law finds a value for
(which had previously been ignored).This
method is not a true solution of Maxwell’s
equations but can provide a good
aproximation for slowly changing fields.

15. 4.CURRENTS SOURCES
If all currents in a system are known(i.e.,if
a complete description of the current
density is available)then the magnetic
field can be determined,at a position
‘r’,from the currents.This technique
works well for problems where the
medium is a vacuum or air or some
similar material with a relative
permeability of 1.For a very difficult
geometry, numerical integration may be

17. When the air gaps are large in comparison
to the magnetic circuit length,fringing
becomes significant and usually requires a
finite element calculation.The finite
element calculation uses a modified form
of the magnetostatics equations above in
order to calculate magnetic potential.The
value can be found from the magnetic
potential.The magnetic field can be
derived from the vector potential.

18. 5.MAGNETIZATION
DEMAGNETIZING FIELD AND
MICROMAGNETICS.
Strongly magnetic
materials(i.e.,ferromagnetic,
ferrimagnetic or paramagnetic) have
a magnetization that is primarly due
to electron spin.Except in metals,
electric currents can be ignored.

19. Thus, the divergence of the
magnetization, has a role analogues to
the electric charge in electrostatics and
is often referred to as an effective
charge density.
The vector potential method can also be
employed with an effective current
density.

20. THANKYOU