Home >> Science & Nature >> Science

DIY Thermocouple

A thermocouple is a device used to measure temperature. It operates using the principle of the Seebeck Effect, which was discovered by Thomas Seebeck. Seebeck found when two dissimilar metals at different temperatures are brought together to form a junction, a voltage is generated. The amount of the voltage created is proportional to the size of the temperature difference between the metals. To make your own thermocouple, use screws and copper circuit wire. The screws should be large enough that the wire can be wrapped around them several times. A small voltage will be generated if one of the screws is heated, and the other will have a much cooler temperature.

Things You'll Need

3 large iron screws
Copper wire
Alligator clips
Bowl of water
Digital multimeter

Instructions

- 1
  Place one of the screws in the freezer and leave it overnight. Heat the bowl of water until the water is steaming by either boiling or microwaving.
- 2
  Cut 1 foot of copper wire, and remove any insulation so the wire is bare. Wrap a portion of the wire around one of the screws so its top and middle are covered. Take the remaining end of the wire, and do the same to the second screw. Be careful to leave at least four inches of space between the screws.
- 3
  Attach the red probe of the multimeter to the bottom of the first screw, and the multimeter's black probe to the bottom of the second screw. Use alligator clips to ensure the probes do not fall off. Switch the multimeter to a DC millivolts setting.
- 4
  Place the top of one of the screws either over the steaming water, or inside the bowl. The multimeter probe must not touch the water, and the second screw must be far enough away so it remains at room temperature. After several seconds, record the voltage reading.
- 5
  Unwind the copper wire from the second screw and replace it with the screw from the freezer. If necessary, reheat the water first. Again, record the voltage with the multimeter.

Science