Conductivity of Glass

Insulating glass becomes a conductor of electricity when heated with a blowtorch.

Two ceramic lightbulb sockets are wired in series to a household AC power cord. When two incandescent bulbs of the same Wattage rating are screwed into the sockets and the cord is plugged in, they both pass the same amount of current and so they both light with the same intensity. When one bulb is unscrewed, the circuit is broken and the other bulb goes out. If we can replace the missing bulb with a conductive material, the circuit will once more be complete and the remaining bulb will light again.

For more details on our setup, see http://sciencedemonstrations.fas.harvard.edu/icb/icb.do?keyword=k16940&pa...

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Category:

Education

Tags:

• conductivity
• resistivity
• ions
• molten glass
• glass
• series circuit
• incandescent lightbulb
• physics demonstration
• Physics
• demonstration experiment
• gerald zani
• Experiment
• Demonstration (teaching)

[tonsilol]

beloved opaque bulbs :-(

[NatSciDemos]

@tonsilol The bulb we removed at 0:15 is not the same as the one we smashed at 0:24--that bulb died a natural death. No incandescent bulbs were harmed in the making of this movie.

[TheMinecraftManiac2]

At the end the melted glass looks sort of like an owl. And before that it looks like a grumpy cat!

[kamalmichael]

r u sure the wires didnt melt ,fused together and made contact? ...although i hv to admit, the light came on very slowly which suggest u r correct

[KakHazhar]

Perfect demo, loved it.