Question

Which one of the following devices is used to measure atmospheric pressure?
A. Ammeter
B. Barometer
C. Potentiometer
D. Lactometer

Answer 1

Hint: The device which is used to measure atmospheric pressure at a place consists of a mercury column in which mercury moves up or down depending on atmospheric pressure at a place. By studying the given options for this property, we can find the correct answer.

Complete step by step answer:
Pressure is defined as the force applied on a surface per unit area of the surface. The expression for pressure is
\[P = \dfrac{F}{A}\]
Barometer is a device used to measure atmospheric pressure at a place. In a barometer, there is a mercury column in which mercury moves up or down depending on atmospheric pressure at a place. It is graduated in millimetres and the unit used for measurements from a barometer is mm Hg.
1mm of Hg = 133.3224 Pa
The atmospheric pressure at the sea level is 76mm of Hg.

So, the correct answer is “Option B”.

Additional Information: There are many units used for measuring pressure. The SI unit of pressure is pascal (Pa). 1Pa=1 newton per square meter.
Atmospheric pressure is defined as the pressure exerted by the atmosphere due to its weight. The SI unit of atmospheric pressure is atm pronounced as atmospheres. It is related to other units of pressure as follows:
1 atm = 101325 Pa
Torr is another unit of pressure which is defined on an absolute scale such that 1 atm = 760 torr.
The atmospheric pressure is maximum at the sea level. The reason for this is that pressure decreases with increase in height in the atmosphere and atmospheric depth is maximum at the sea level. Under the sea level, pressure increases at greater speed because water exerts additional pressure and pressure increases by 1atm after every 10m depth under the sea level.

Note: 1. An ammeter is an electrical device which is used to measure the amount of current in a circuit.
2. A potentiometer acts as a device which can offer variable resistance.
3. A lactometer is a device which is used to measure the amount of water in a given quantity of milk.