Ifvwe touch a plasma ball with our hand we feel nothing,but when touched by keeping an aluminum foil over the ball we feel an electric shock. Why?
Ifvwe touch a plasma ball with our hand we feel nothing,but when touched by keeping an aluminum foil over the ball we feel an electric shock. Why?
The electrode in the centre produces a high frequency, high voltage electric field. It forms one plate of a capacitor with the other plate infinitely far away. The discharges form more or less randomly.
When you touch the glass, you act as the other plate of a capacitor with the glass as a dielectric between you and the plasma. You (or your fingertips) being close to the glass change the electric field pattern in such a way that the plasma discharge seems to follow your fingers. That has nothing to do with a current flowing through the glass but only with the electric field penetrating the glass. Now, insulators do not stop electric fields, conductors do. If glass was not an insulator, you touching the glass would do nothing apart from giving you a nasty shock if the glass wasn’t grounded, as you couldn’t change the patterns of the electric field lines inside the globe.
So yes, glass is an insulator. If it wasn’t the plasma ball would work. Your fingers change the electric field, and do not draw a current from the inside of the globe
The electrode in the centre produces a high frequency, high voltage electric field. It forms one plate of a capacitor with the other plate infinitely far away. The discharges form more or less randomly.
When you touch the glass, you act as the other plate of a capacitor with the glass as a dielectric between you and the plasma. You (or your fingertips) being close to the glass change the electric field pattern in such a way that the plasma discharge seems to follow your fingers. That has nothing to do with a current flowing through the glass but only with the electric field penetrating the glass. Now, insulators do not stop electric fields, conductors do. If glass was not an insulator, you touching the glass would do nothing apart from giving you a nasty shock if the glass wasn’t grounded, as you couldn’t change the patterns of the electric field lines inside the globe.
So yes, glass is an insulator. If it wasn’t the plasma ball would work. Your fingers change the electric field, and do not draw a current from the inside of the globe
