Answer & Explanation
Air Pressure can be defined as the pressure of air in the earth's atmosphere. It reaches a maximum of about 100,000 Pa near sea level and decreases as altitude increases.
The barometer is an instrument which is used for measuring Air pressure.
Physics instruments and their uses:
Barkometer - - - Tanning liquors used in tanning leather
Bolometer - - - Electromagnetic radiation
Spectrometer - - - Properties of light.