Uploaded May 2020 | Updated September 2026, 11 hours ago
Glass is usually a good electricity insulator but heated to a high temperature it conducts electricity very well. The normally immobile electrons in the glass are raised to the conduction band by the high temperature.
Two lamps are wired in series to a household AC power cord. When two incandescent lamps 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 lamp is unscrewed, the circuit is broken and the other lamp goes out. If we can replace the missing lamp with a conductive material, the circuit will once more be complete and the remaining lamp will light again.
Glass is usually a good electricity insulator but heated to a high temperature it conducts electricity very well. The normally immobile electrons in the glass are raised to the conduction band by the high temperature.
Two lamps are wired in series to a household AC power cord. When two incandescent lamps 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 lamp is unscrewed, the circuit is broken and the other lamp goes out. If we can replace the missing lamp with a conductive material, the circuit will once more be complete and the remaining lamp will light again.
