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DEM22 Electrical Conduction of Glass

Objective:

– To demonstrate that glass will conduct electricity at high temperature.

Apparatus:

  • Glass conduction apparatus, c/w:
  • 250 watt lamp, ceramic “melting socket,” line cord
  • Propane torch
  • Glass element carefully prepared and pre-tested
  • Isolation transformer

DEM22 - Electrical Conduction of Glass

Method:

The series circuit containing the glass element and lamp bulb is open-circuited at room temperature. If the element is heated on one flat side to melting point, then due to the high negative resistance — temperature coefficient of glass, the conductivity increases rapidly, and at a bright red heat the P=I2R loss in the glass is sufficient to maintain the temperature without further use of the flame.

Note:

    1. Ensure that the A.C. switch on the conduction apparatus is on.
    2. Heat the glass element on the flat side of the glass mount/stem only. Otherwise, the sagging molten glass may collapse, causing the internal conductors to short together.
    3. Please wear gloves when handling hot bulbs.
    4. Remember to replace the shorted light bulb with broken glass shell after each demo.

 

Electrical Conduction of Glass  – video not produced by BCIT

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