Delhi Police Constable Exam Model Paper 10

The correct answer is Used to measure atmospheric pressure.
CONCEPT:
Barometer:

●A barometer is a scientific instrument that is used to measure air pressure.
● The height of the level of mercury in the tube is nearly76 cm above the free level of mercury in the trough.
● Formula to calculate the atmospheric pressure is, ${\mathit{P}}_{\mathit{a}}=\mathit{\rho }\mathit{g}\mathit{h}$
● The reading in the barometer can be calculated by the formula
$\mathit{h}=\frac{{\mathit{p}}_{\mathit{a}}}{\mathit{p}\mathit{g}}$
Where, ρ = density of mercury, g = acceleration due to gravity, and h = vertical distance.
EXPLANATION:
● From above it is clear that the mercury column in the barometer is used to measure atmospheric temperature
Extra point:
This are some of the device and their application

Device	Application
Barometer	atmospheric pressure
Anemometer	Airspeed and direction
rain gauge	Amount of rainfall
seismometer	Intensity of earthquake