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Electrical Resistance and Temperature

This demo illustrate how the electrical resistance of a material depends on temperature. A sample of material is warm up with a hair dryer, then cool down with liquid nitrogen. A sample of copper wire winded in a coil works well to illustrate the typical behavior of electrical resistance in metals. The response of a thermistor can be used to illustrate how different materials can have very different behaviors.
ID: d0023
Set up time:
5 min to get LN2 on a small thermos; 2 minutes in class.
Requires:
Electrical Outlet. Components.
Notes:
You may need assistance the first time you use this demo.Check to see if LN2 is available. It the tank is empty, it will take about a week to get more. By all means teach your students how to handle LN2 in a safe manner -- at a minimum, wear protective goggles.
Figures:
Documents:
Comments:

Table of Components

Qty. name location notes
1 Coil of copper wire W106; North Cabinets; U4-L2
1 Thermistor W106; South Wooden Shelves; U3-L1 (clear box)
1 heat gun W104; South Shelves; U4
1 Multimeter W106; East Wall; on top of small metallic drawers
2 alligator clips "
2 12-in banana cable W104; West Wall;
1 Thermos W106; Under Sink
LN2 W106; Under Sink; Big Dewar
Googles W106; Above Sink;