# Question #1bc13

May 16, 2017

#### Explanation:

Since temperature changes are continuous, we need to use something that changes continuously with the temperature.

a) A metal bar expands (changes its length) as it is heated, so we could use the changing length as a measure of temperature.

b) A liquid that changes colour suddenly at 100 °C would not be very useful.

All it would tell you is when the temperature is 100 °C.

c) According to Gay-Lussac's Pressure Temperature Law, the pressure $p$ of a given amount of gas at constant volume is directly proportional to the Kelvin temperature $T$.

$\textcolor{b l u e}{\overline{\underline{| \textcolor{w h i t e}{\frac{a}{a}} p = k T \textcolor{w h i t e}{\frac{a}{a}} |}}} \text{ }$

Thus, we could use the pressure as a measure of the temperature.

d) Liquid mercury expands as the temperature increases.

Thus, we can use mercury in a thin tube to measure temperature.

(From www.lifeworker.com)

As the mercury in the thermometer bulb expands, it moves through a thin capillary graduated in degrees.

The clinical thermometer above shows a temperature of 36.5 °C.