Table of Thermodynamics Demonstration

Thermodynamics Equipment List

Lecture Demonstrations

Bimetallic Strip, 4A30.10a

Topic and Concept:

Location:

4A30-10a-01a.jpg

Abstract:

A bimetal strip of brass and steel is heated in a Bunsen burner flame and then cooled with liquid nitrogen.

Equipment

Location

ID Number

Bimetallic Strip

TD, A3, Shelf #1

Burner

location

NA

Liquid nitrogen

location

NA

Safety glove and glasses

location

NA

Red and white gas carts

Rooms 2103, 2241, (and 2223 upon request)

Important Setup Notes:

Setup and Procedure:

  1. To light the burner, connect the attached gas hose to the gas out (red panel) on the red and white gas cart.

  2. Open the gas valve.
  3. Light a match and bring it near the top of the burner.
  4. The flame will ignite the gas. Adjust the flame height accordingly by adjusting the valve.
  5. Heat the strip in the flame and watch as it bends toward the stainless steel side.
  6. Turn of the flame by closing the gas valve.
  7. Dip the strip into the liquid nitrogen and watch as the strip bends toward the brass side.

Cautions, Warnings, or Safety Concerns:

Discussion:

The bimetallic strip consists of brass and stainless steel. Since brass has a higher coefficient of thermal expansion than stainless steel, it expands more for a given change in temperature than does the stainless steel side. Thus, when heated, the strip bends to the stainless steel side. On the other hand, when the strip is placed in liquid nitrogen (77K), the brass contracts more for a given change in temperature than does the stainless steel causing the strip to bend in the opposite direction.

4A30-10a-01i.jpg

4A30-10a-03-250.jpg

Videos:

References:

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fw: BiStrip (last edited 2013-07-18 20:33:54 by srnarf)