Plasma ball is aspherical glass ball filled with a rare gas (1-10 mm Hg) and central electrode. Base of the ball contains electical oscillating circuit, which power up the ball with high voltage about 10 000 V and polarity changing with frequency about 35 000 Hz.

After plugging in of the device from the middle of the ball appears many "glowing fibres". Thanks plasma ball we are able to observe many interesting phenomenas, for example:
a) slow rising of the fibres,
b) with closing the finger to the ball fibres are concentraded in its ditection and follows the finger when we move it,
c) closing to ball energy saving bulb we can observe its glowing.

The name of that toy is taken from the fact, that indeed inside is created plasma. Plasma is a strongly ionized gas; ions, which under the normal conditions are present in all gases due to natural radioactivity, inside shpere are moved by electric field. If mean distance (mean free path) between particles is not too small, they obtain an energy enough to ionize and excite another ones by collisions. Excited molecules loose energy by radiation of the electromagnetic waves, also in visible range.

Fibres follows to the top, because their temperature is quite high and their density is lower than rest od the gas in the ball. Fibres concentrate into a finger because is is on the ground potential equal 0V: difference of the potentials between central electrode and a finger is much higher whan between central electrode and any other point on the surface of the ball. Concentration in touched place is caused by biggest in that place intensity of the electric field. Around plasma ball is created alternate electromagnetic field, which causes excitation of the gas particles in energy saving bulb and its glowing.