5D20.60 • Resistivity and Temperature: Conduction in Glass at High Temperature

Photo and Video Shows the Apparatus Used by the University of Texas at Austin.

Instructions/Notes:

• This is a step up transformer. CAUTION: LETHAL VOLTAGE.
• Please, keep clear of any part of the apparatus above the table top.
• Turn on the gas on the side of the teaching console.
• Using the provided lighter, ignite the Bunsen burner.
• Turn on the voltage by flipping red switch at the base of the demo.
• Place the burner under the glass rod.
• When the glass begins conducting, remove the burner and turn off gas.

Concept Conveyed:

• Demo uses an insulating glass rod clipped between electrodes with a voltage applied across it, demonstrating that glass can conduct under high temperatures.
• When the glass is initially heated, the air will conduct.
• After about 30 seconds, the glass will develop charge carriers and begin conducting.

Demo Staff:

• This demo uses Jacob's Ladder base, please remove Jacob's Ladder and replace with glass conducting demo on the top of the base.
• Please remember to put Jacob's Ladder back onto the base once finished!
• Be sure to include a lighter with demo.
• Clip glass rods onto apparatus by placing clips below the rod.
• Attach burner tube to gas port on the side of the teaching console.
• In the classroom, ground Bunsen burner by clipping one end of a wire to the burner itself and the other end to a port next to the gas port (refer to photo of setup below).

Last updated on September 18, 2025