There are four types of evacuated tubes, known as Crookes Tubes: The Maltese Cross, The Paddle Wheel, The Magnetic Effect and The Electrostatic Deflection. They are used to demonstrate properties of electrons. Crookes tubes are constructed from highly evacuated glass chambers and are therefore fragile. They need to be handled with great care and mounted in the holders provided before any connections are made or experiments are conducted.
The Electrostatic Deflection
Consists of a thin aluminium sheet with a thin slit in it near one electrode. The slit allows a narrow beam of electrons to pass through the opening that impact a phosphor coated screen along the length of the tube. When energized, the tube produces a bright green line on the phosphor screen clearly showing the electron beam. The Electrostatic Deflection version contains two additional electrodes that allow the user to apply voltages and deflect the electron beam in a similar manner and observe the results on the phosphor screen.
Three items are required to operate the unit:
- A variable DC power supply, 2-12 V. Haines item 2633-001 IEC power pack is suitable.
- A source of high voltage direct current. Haines item EM013301 Induction (rumkoff) coil is suitable
- Two sets of connecting leads, one set with banana plugs and the other set with alligator clips.