BM / IDAF / Physik Englisch IDAF Vortrag - AUSWENDIG KÖNNEN

Checking the Accuracy

• “But building a thermometer is only half the challenge. The real question is: how accurate is it?”
• A homemade thermometer can work surprisingly well, but small errors can affect the result.
• The scale has to be calibrated correctly. We also have to read the liquid level carefully, place the thermometer at the correct depth in the water, and wait until the temperature is stable.
• Even an air bubble, a leak or a small reading error can change the measured temperature.

So how can we check the accuracy?

• We compare the temperature shown by our homemade thermometer with the temperature shown by an electronic thermometer.
• The electronic thermometer gives us the reference value. The difference between the two values shows how accurate our thermometer is. The smaller the difference, the more accurate our measurement is.

(Mistakes that happened)

• [Short pause.]
• During the experiment, I also experienced how sensitive such a simple instrument can be.
• While I was rebuilding my thermometer, the thin glass tube broke.
• It was only one small part, but without it, the whole thermometer could no longer work as it should.
• For me, this showed that accurate measurements do not only depend on understanding the physics. They also depend on careful construction and controlling possible errors.

And this brings us back to Galileo.

• More than 400 years ago, his thermoscope could make a temperature change visible. But it could not reliably tell him:

• “The temperature is exactly 25 degrees.”

• The important development was learning how to turn this visible change into a reliable measurement.

• At the beginning of our presentation, we asked whether Galileo’s thermoscope was already a real thermometer.

• Now we know the difference.

• Galileo made temperature change visible.

• [Short pause. Look at the audience.]

• The thermometer made it measurable.