The Earth has a magnetic field that extends into space and protects the planet. The magnetic field is generated by Earth's core and behaves like a giant bar magnet. It has a north and south magnetic pole that are located near the geographic poles but can wander over time. The magnetic field deflects solar winds and cosmic rays, protecting the atmosphere. It can be mapped and measured at different locations on Earth. Animals like birds are able to detect the magnetic field to aid navigation.

1. Earth magnetic field

2. PREPARED BY
CHELANI PRASHANT A

3. EARTH MAGNETIC FIELD

4. EARTH MAGNETIC
FIELD
introduction
 Earth's magnetic field, also
known as the geomagnetic field, is the
magnetic field that extends from the
Earth's interior out into space, where
it meets the solar wind, a stream of
charged particles emanating from the
Sun.
 Its magnitude at the Earth's surface
ranges from 25 to 65 microteslas
(0.25 to 0.65 gauss).
 The North geomagnetic pole,
located near Greenland in the northern
hemisphere, is actually the south pole
of the Earth's magnetic field, and the
South geomagnetic pole is the north
pole. Unlike a bar magnet, however,
Earth's magnetic field changes over
time because it is generated by a
geodynamo

5. The North and South magnetic poles wander
widely over geological time scales, but sufficiently slowly for
ordinary compasses to remain useful for navigation.
The magnetosphere is the region above the
ionosphere and extends several tens of thousands of kilometers
into space, protecting the Earth from the charged particles of
the solar wind and cosmic rays that would otherwise strip away
the upper atmosphere, including the ozone layer that protects
the Earth from harmful ultraviolet radiation.

6. William Gilbert and
the Birth of Magnetism
 Personal Physician to Elizabeth I
 Published De Magnete in 1600, a
6-volume treatise documenting his
experiments with magnetism
 Proposed that Earth behaves like
a giant bar magnet
 Died in 1603 of bubonic plague William Gilbert,
1544-1603

7.  At any location, the Earth's magnetic field
can be represented by a three-dimensional
vector.. Its angle relative to true North is
the declination (D) or variation. Facing
magnetic North, the angle the field makes
with the horizontal is the inclination (I) or
magnetic dip. The intensity (F) of the field
is proportional to the force it exerts on a
magnet. Another common representation is in
X (North), Y (East) and Z (Down) coordinates

8. INCLINATION
 angle measured from horizontal  angle measured from geographic
north
DECLINATION

9. intensity
The intensity of the field is often measured in gauss (G),
but is generally reported in nanoteslas (nT), with 1 G = 100,000 nT. A
nanotesla is also referred to as a gamma (γ).The tesla is the SI unit of
the Magnetic field, B. The field ranges between approximately 25,000
and 65,000 nT (0.25–0.65 G). By comparison, a strong refrigerator
magnet has a field of about 100 gauss (0.010 T).

10. Dipole model of the
Earth's magnetic field
 The dipole model of the
Earth's magnetic field is a
first order approximation of
the rather complex true
Earth's magnetic field. Due
to effects of the
interplanetary magnetic
field, and the solar wind,
the dipole model is
particularly inaccurate at
high L-shells (e.g., above
L=3), but may be a good
approximation for lower L-
shells. For more precise
work, or for any work at
higher L-shells, a more
accurate model that
incorporates solar effects,

11. MAGNETOSPHERE Solar wind = charged
particles ejected
from the Sun
Magnetosphere = a
zone of charged
particles trapped by
Earth’s magnetic
field
Magnetotail = portion
of a magnetosphere
that is pushed away
from the sun by the
solar wind

12. EARTH'S CORE AND
THE GEODYNAMO
The Earth and most of
the planets in the Solar System,
as well as the Sun and other
stars, all generate magnetic fields
through the motion of electrically
conducting
The mechanism by
which the Earth generates a
magnetic field is known as a
dynamo.
The magnetic field is
generated by a feedback loop:
current loops generate magnetic
fields a changing magnetic field
generates an electric field
(Faraday's law) and the electric
and magnetic fields exert a force
on the charges that are flowing in
currents (the Lorentz force).

13.  In 1995, the first
computer model was
published (Glatzmaier-
Roberts model) which
successfully simulated the
geodynamo, including
spontaneous reversal
 Since then, several other
groups have also succeeded
Computer Model of the Geodynamo

14. MEASUREMENT
AND ANALYSIS  The Earth's magnetic field
strength was measured by Carl
Friedrich Gauss in 1835 and has
been repeatedly measured since
then, showing a relative decay
of about 10% over the last 150
years.
 Governments sometimes
operate units that specialize in
measurement of the Earth's
magnetic field. These are
geomagnetic observatories,
typically part of a national
Geological survey, for example
the British Geological Survey's
Eskdalemuir Observatory

15. Example of analysis

16. BIOMAGNETISM
Animals including birds and turtles can detect
the Earth's magnetic field, and use the field to navigate
during migration. Cows and wild deer tend to align their
bodies north-south while relaxing, but not when the animals
are under high voltage power lines, leading researchers to
believe magnetism is responsible.
Researchers found out that very weak
electromagnetic fields disrupt the magnetic compass used
by European robins and other songbirds to navigate using
the Earth's magnetic field. Neither power lines nor cellphone
signals are to blame for the electromagnetic field effect on
the birds,.

18. THANK YOU