3B SCIENTIFIC PHYSICS U19153 Manuel D'utilisation page 5

3B SCIENTIFIC ® PHYSICS
Instruction sheet
08/08 ALF
1. Safety instructions
Hot cathode tubes are thin-walled, highly evacu-
ated glass tubes. Treat them carefully as there is a
risk of implosion.
•
Do not subject the tube to mechanical stresses.
•
Do not subject the connection leads to any
tension.
•
The tube may only be used with tube holder D
(U19100).
If voltage or current is too high or the cathode is at
the wrong temperature, it can lead to the tube
becoming destroyed.
•
Do not exceed the stated operating parame-
ters.
•
Only change circuits with power supply equip-
ment switched off.
•
Only exchange tubes with power supply
equipment switched off.
Maltese Cross Tube D U19153
When the tube is in operation, the stock of the tube
may get hot.
•
If necessary, allow the tube to cool before
dismantling.
The compliance with the EC directive on electro-
magnetic compatibility is only guaranteed when
using the recommended power supplies.
The Maltese cross tube is used to demonstrate how
cathode rays propagate in straight lines in the
absence of any electric or magnetic field. This is
shown by placing a Maltese cross in the path of the
beam to throw a shadow on a fluorescent screen.
The tube is also used to show how beams can be
focussed by magnetic fields. This serves as an in-
troduction to electron optics.
The Maltese cross tube is a highly evacuated tube
with an electron gun consisting of a pure tungsten,
1
1 4-mm sockets for filament
and cathode
2 Electron gun
3 4-mm plug for connecting
anode
4 Boss with 4-mm plug
connected to Maltese cross
5 Maltese cross
6 Fluorescent screen
7 Boss
2. Description