In calibrating a thermometer by setting only the freezing and boiling points, what assumptions are you making regarding the internal diameter of the thermometer and the expansion of alcohol?
You are assuming that the capillary bore is constant diameter and that the expansion of the fluid (whether it is Hg, alcohol, or any other liquid) is constant with temperature.
When calibrating a thermometer by setting only the freezing and boiling points, you are making certain assumptions regarding the internal diameter of the thermometer and the expansion of alcohol. Specifically, two assumptions can be made:
1. Assumption about the internal diameter: It is assumed that the internal diameter of the thermometer remains constant throughout the temperature range being measured. This assumption is important because it allows for consistent expansion or contraction of the liquid inside the thermometer.
2. Assumption about the expansion of alcohol: It is assumed that the alcohol used in the thermometer expands uniformly with temperature changes. This means that the expansion of the alcohol will be proportional to the change in temperature, indicating a linear relationship between temperature and the volume of the liquid.
By assuming both a constant internal diameter and uniform expansion of the alcohol, it becomes possible to calibrate the thermometer based on two fixed reference points (freezing and boiling points of water) and interpolate temperature readings for other points along the scale.
It is important to note that these assumptions are typically valid for simple glass thermometers with a narrow range of temperatures. However, for more precise measurements and broader temperature ranges, different assumptions and calibration techniques may be necessary.