A picture tube is an insulator. The electrons would gather up and so, create an electric charge when the TV is on. If it was a conductor, the charge would not build up. Hope this helps :)
insulator
It is an insulator.
its an insulator
insulator.
Insulator
Insulator
insulator
Insulator
it’s a insulator
an insulator
Rubber is an insulator for normal voltages.