when taking the temp of water, why should u keep the bulb of the thermometer from touching bottom or sides?

Question

of the cylinder

Answer 1

Because the side of the cylinder is of a different composition and may have a very different temperature. Moreover, having the bulb in contact means that there is no water left between the thermometer and the cylinder, which means heat can transfer directly, this could damage the thermometer at worst, and completely falsify the reading at best.

Answer 2

Yeah, but it doesn't even have to be a metal pot - it can be a glass test tube, your metal container, anything else you're heating a fluid in.

The problem, as was alluded to but not directly stated, deals with thermodynamics. When your bulb touches the side of any container, there's an energy transfer between the atoms in the thermometer fluid reservoir and the container material In fact, this happens when the surfaces of any two objects come into contact with each other, and it's called conduction.

Let's use an example. Let's say you're boiling water in a glass beaker. The glass will be considerably warmer than the water in it, and therefore will possess more heat energy than the water. If you touch the thermometer reservoir to the glass, the heat energy of the glass will be imparted upon the thermometer fluid, increasing its temperature and causing it to rise and give a false reading.

Therefore, it's critically important to keep the bulb right in the middle of the fluid you're testing, so you get an accurate temperature reading

Answer 3

Because the metal of the pot readily conducts heat you will be measuring the temperature applied to the pot which will not be representative of the water temp

Answer 4

Because they may be at a different temperature to the water?

Answer 5

because glass will be hotter and would effect ur results