3B Scientific Air Cushion Plate - Handbuch (Seite 89)

Physical Experiments on the Air-Cushion Table
38
Result:
The hover discs move towards the opposite elec-
trode on a parabolic path.
Interpretation:
Electrons are subject to a force in the electric
field. When the electrons in a vacuum enter an
electric field at a perpendicular angle to the field
lines, they are forced onto parabolic paths. Their
velocity increases in this process.
Note:
It is recommended to conduct this experiment with-
out an electric field at first, in order to demonstrate
the straight, uniform movement of the electrons.
2.4.3 Motion of Electrons in a Vacuum Under
the Influence of an Electric Field
Components:
Air-cushion table with fan
Overhead projector
Electrode
2 Pieces
Magnetic barrier, short 1 Piece
Aluminum hover disc 5 Pieces
Plastic tweezers 1 Piece
High-voltage source
Model simulation
Real Object Model
Vacuum containing Experiment surface of
an electric field the air-cushion table
Electrodes Electrodes
Electrons Hover discs made of
aluminum
How to proceed:
Carefully align the air-cushion table in a hori-
zontal position using the spirit levels. Arrange
the electrodes at the edges of the experiment sur-
face parallel to each other. The electrode on side
no. 2 is set on its bases, whereas the bases of the
other electrode point upwards. Place the magnetic
barrier, turned by 180°, closely to the experiment
surface parallel to the electrode on side no. 2, so
that the hover discs cling to it due to the mag-
netic attraction. Connect the electrodes to the
high-voltage source in such way that the anode
is located next to the magnetic barrier. Then place
the hover discs onto the cathode.
Feed d.c. voltage to the electrodes and turn the
fan to a medium setting. Then lift the hover discs
off the cathode using the tweezers and place them
onto the experiment surface one by one, position-
ing them directly in front of the cathode. Observe
their motions between the electrodes.
Result:
The hover discs move from one electrode to the
other in an accelerated way.
Interpretation:
The electrons in a vacuum will move in an accel-
erated way from the cathode to the anode under
the influence of an electric field.
2.4.4 Principle of Electric Conduction
Components:
Air-cushion table with fan
Overhead projector
Electrode
2 Pieces
Hover disc made of aluminum 5 Pieces
Plastic tweezers
1 Piece
High-voltage source