It is essential that all HT connectors and cables are rated at the voltage to be used. HT (high tension) power supplies (generally supplying voltages up to 400 V) can cause fatal electric shock. Demonstration meter with a centre zero dial, - 2.5 mA.

Power supply, 6.3 V, AC, for the heater filament (this is often included on the HT supply).You can also use the apparatus to demonstrate a valve diode – a device that lets the current flow in just one direction. The main purpose of this experiment is to explain the principle of an electron gun.

The deflection tube has the advantage that you can, if you want, analyze the shape of the path. Most of these ideas can be demonstrated by either a fine beam tube or a deflection tube.

Beams of electrons or cathode rays have applications – like televisions and cathode ray oscilloscope (CRO) tubes.

Beams of electrons can be deflected in magnetic fields (in circles).

Beams of electrons can be deflected in an electric field (in parabolas).

Hot cathodes (which are negative) produce beams of electrons.

Your choice of which tubes and experiments to use is likely to be determined by what apparatus you have available. However, all electron tubes have the same basic construction: an evacuated glass bulb with a metal plate that is heated by a small filament. They are appropriate for advanced level courses, and sometimes intermediate level courses.Įach of the experiments uses an electron tube (see 'Types of electron tube') with slightly different features from the others. The experiments in this collection demonstrate the existence and some of the properties of electrons and electron beams.

Cathode ray experiment for dummies