General Precautions - 3B SCIENTIFIC PHYSICS U8495258 Instructions D'utilisation

3. Operation

3.1 General precautions

•
Protect the instrument from moisture, dust and
mechanical shocks.
•
Avoid touching the magnet needle.
The geometry of the earth's magnetic field lines can
be greatly altered by static magnetic fields, steel
frames of laboratory benches and equipment, and
steel supports in the floor, ceiling and walls of
buildings. For this reason the measured angles may
sometimes differ widely from the expected values.
3.2 Inclination
The magnet needle aligns itself along the direction
of the earth's magnetic field.
•
With the scale ring in the horizontal plane, turn
the instrument so that the blue end of the
magnet needle is at 0° (the blue end of the
needle is its north-seeking pole).
•
Next use the hand-wheel to turn the cradle
through 90° (the plane of the scale ring is then
vertical). The blue end of the magnet needle is
inclined downwards.
The angle between the magnet needle and the
horizontal plane is called the inclination. It differs
from place to place. At a latitude of about 50° north
(Europe) the inclination is 63° to 68°.
3.3 Declination
The horizontal deviation of the magnet needle from
the direction of the geographical north pole is called
the declination.
•
With the scale ring in the horizontal plane, turn
the instrument so that the blue end of the
magnet needle points to the angle on the scale
ring corresponding to the angle of declination
for the place where you are.
The 0° axis of the scale ring is then lying along the
geographical north-south axis.
3.4 Magnetic effect of an electric current
In order to carry out the experiment, a variable DC
current source is also needed, such as:
DC power supply 0-20 V, 0-5 A
or
DC power supply 0-20 V, 0-5 A
•
With the scale ring in the horizontal plane, turn
the instrument so that the blue end of the
magnet needle (its north-seeking pole) is at 0°.
•
Connect the sockets on the instrument to a
variable DC current source.
As the current is increased, the needle is deflected
increasingly from its original direction.
Elwe Didactic GmbH • Steinfelsstr. 6 • 08248 Klingenthal • Germany • www.elwedidactic.com
3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany • www.3bscientific.com
When the polarity is reversed, the direction of the
deflection changes.
U33020-230
U33020-115.
Subject to technical amendments
© Copyright 2010 3B Scientific GmbH