Thermometer And Its Types MCQ - Practice Questions with Answers

Thermometry: It is a branch of science that deals with the measurement of the temperature of a substance is known as thermometry.

An instrument used to measure the temperature of a body is called a Thermometer. The principle on which it works is by absorbing heat from the body.

There are various kinds of thermometers which are briefly classified into three types - 

• - Liquid thermometers - In liquid thermometers, mercury is usually preferred over other liquids. The reason behind this is its expansion is large and uniform. The main reason behind all these is that it has high thermal conductivity and low specific heat.

  Range of temperature: (freezing point of mercury) - (boiling point of mercury) which is $-50^{\circ} \mathrm{C}$ to $350^{\circ} \mathrm{C}$

  The formula for calculation of temperature at any length I:

  $$
  t=\frac{l-l_0}{l_{100}-l_0} \times 100^0 \mathrm{C}
  $$

  
  Here $-l=$ length of the mercury column at the given temperature $t$.
  $l_{0=}$ length of the mercury column at the $0^{\circ} \mathrm{C}$ temperature
  $l_{100}=$ length of the mercury column at the $100^{\circ} \mathrm{C}$ temperature

• Gas thermometers: In this gases are used as thermometric material. Gas thermometers are more sensitive and accurate than liquid thermometers as the expansion of gases is more than that of liquids. This gas used as a thermoelectric substance is called an ideal gas thermometer. These are basically two types

(i) Constant pressure gas thermometers - If pressure is constant, then for an ideal gas, volume is directly proportional to temperature. So, 

$$
V \alpha T
$$

The formula for the calculation of temperature at any volume V: $t=\frac{V-V_0}{V_{100}-V_0} \times 100^0 \mathrm{C}$

Here, $V=$ length of the mercury column at the given temperature $t$. $V_0=$ length of the mercury column at the $0^{\circ} \mathrm{C}$ temperature. $V_{100}=$ length of the mercury column at the $100^{\circ} \mathrm{C}$ temperature.

(i) Constant volume gas thermometers - If the volume is constant, then for ideal gas, pressure is directly proportional to temperature. So, 

$P \alpha T$

The formula for calculation of temperature at any pressure $\mathrm{P}: \quad t=\frac{P-P_0}{P_{100}-P_0} \times 100^0 \mathrm{C}$
Here, $P=$ length of the mercury column at the given temperature $t$.
$P_{100}=$ length of the mercury column at the $100^{\circ} \mathrm{C}$ temperature.

• Resistance thermometers: Usually Platinum and Germanium are used in resistance thermometers due to their high melting point and large value of temperature coefficient of resistance. This type of thermometer can be used for high temperatures. 

The formula for calculation of temperature at any resistance R : $t=\frac{R-R_0}{R_{100}-R_0} \times 100^0 \mathrm{C}$
Here, $R=$ length of the mercury column at the given temperature $t$.
$R_{0=}$ length of the mercury column at the $0^{\circ} \mathrm{C}$ temperature.
$R_{100}=$ length of the mercury column at the $100^{\circ} \mathrm{C}$ temperature.