3B SCIENTIFIC® PHYSICS
1
Diode D U191501
Instruction sheet
02/08 ALF
1 4-mm plug for connect-
ing
anode
2 .Anode
3 Boss
4 Cathode filament
5 Filament backing plate
6 4-mm sockets for
cathode and filament
1. Safety instructions
Hot cathode tubes are thin-walled, highly evacuated
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.
If voltage or current is too high or the cathode is at
the wrong temperature, it can lead to the tube be-
coming destroyed.
•
Do not exceed the stated operating parameters.
When the tube is in operation, the terminals of the
tube may be at high voltages with which it is dan-
gerous to come into contact.
•
Only change circuits with power supply equip-
ment switched off.
•
Only exchange tubes with power supply equip-
ment switched off.
When the tube is in operation, the stock of the tube
may get hot.
•
Allow the tube to cool before dismantling.
The tube may only be used with tube holder D
(U19100).
The compliance with the EC directive on electro-
magnetic compatibility is only guaranteed when
using the recommended power supplies.
2. Description
The diode allows basic experiments to be performed
on the Edison effect (thermionic effect), demon-
strates how the emission current depends on the
power supplied to heat the hot cathode, allows
recording diode characteristics and shows the use of
the diode as a rectifier.
The diode is a highly evacuated tube with a pure
tungsten heater filament (cathode) and a circular
metal plate (anode) inside a clear glass bulb. The
cathode filament and the anode plate are parallel
to one another. This planar configuration corre-
sponds to the conventional symbol for a diode. A
circular metal plate is attached to one of the fila-
ment leads. This ensures that the electric field be-
tween the anode and cathode is uniform.
