General Precautions - 3B SCIENTIFIC PHYSICS 1003192 Mode D'emploi

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 Measurement of the 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 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 Magnetic effect of an electric current
In order to carry out the experiment, a variable DC
current source is also needed, such as:
1 D C p o w e r s u p p l y 0 - 2 0 V , 0 - 5 A ( 2 3 0
V , 5 0 / 6 0 Hz ) U 3 3 0 2 0 - 2 3 0
o r
1 DC power supply 0 - 20 V, 0 - 5 A (115 V, 50/60 Hz)

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.
When the polarity is reversed, the direction of the
deflection changes.
U33020-115
Subject to technical amendments
© Copyright 2008 3B Scientific GmbH