What is a Barometer?
Italian scientist Evangelista Torricelli invented the barometer. It is an instrument used to measure air pressure as it varies with distance, either above or below sea level.
Types of Barometers
A barometer is an instrument used to measure air pressure as it varies with distance, either above or below sea level. There are two types of barometers, they are:
Mercury Barometer: A mercury barometer is a type of barometer in which the atmospheric pressure balances a column of mercury and the height of which can be exactly measured. Mercury barometers are often corrected to increase their accuracy for ambient temperature and the local value of gravity.
Aneroid Barometer: An aneroid barometer is a barometer which is non-liquid, and because of its smaller size and suitability, it is extensively used in aircraft altimeters and portable instruments. It comprises an evacuated capsule which is flexible-walled, and the wall deflects with variations in atmospheric pressure.
Important Questions on Barometer
1) Why do fluids exert pressure?
The particles in the fluid can move in all directions; this is the reason why the fluid exerts pressure in all directions. Continuous collisions are produced due to the continuous movement of these molecules. The collision results in pressure, which is exerted in all directions.
2) 15 bars equals to _____ Pascals.
a) 100 Pa
b) 1.5 x 106 Pa
c) 100000 Pa
d) 105 Pa
Correct Option: (b)
Explanation: Bar does not fall under the SI units, but it is a metric unit of pressure. One bar is precisely equal to 100,000 Pascals, which is taken from the atmospheric pressure on the earth at sea level.
3) The pressure at any given point of a non-moving fluid is called ________.
a) Differential pressure
b) Fluid pressure
c) Gauge pressure
d) Hydrostatic pressure
Correct Option: (d)
Explanation: With the increase in depth, the hydrostatic pressure fluctuates. Because of the increasing weight of the fluid, hydrostatic pressure is measured from the surface of the fluid. From the surface of the water, the fluid exerts a downward force, making it a non-moving fluid.
4) What is a barometer?
A barometer is an instrument used to measure air pressure as it varies with distance, either above or below sea level. It was invented by the Italian scientist Evangelista Torricelli.
5) How many types of barometers are there?
A barometer is an instrument used to measure air pressure as it varies with distance, either above or below sea level. There are two types of barometers, they are:
Mercury Barometer
Aneroid Barometer
6) What is a mercury barometer?
Atmospheric pressure balances a column of mercury in the mercury barometer, the height of which can be exactly measured. Mercury barometers are often corrected to increase their accuracy for ambient temperature and the local value of gravity.
7) What is an aneroid barometer?
An aneroid barometer is a barometer which is non-liquid, and because of its smaller size and suitability, it is extensively used in aircraft altimeters and portable instruments. It comprises an evacuated capsule which is flexible-walled, and the wall deflects with variations in atmospheric pressure.
8) Viscosity is the measure of the ___________.
a) Hindrance to flow of an object
b) Hindrance to flow of air
c) Resistance to flow of fluid
d) None of these
Correct Option: (c)
Explanation: Due to the relative motion between two surfaces of fluids, viscosity is developed at different velocities. This phenomenon happens due to the development of shear stress on the surface of the fluid.
9) For which kind of process the pressure variation for compressible fluid is maximum?
a) Isothermal
b) Adiabatic
c) Quasistatic
d) None of the mentioned
Correct Option: (a)
Explanation: For the isothermal process, the pressure variation for compressible fluid is maximum due to constant temperature.
10) The pressure measurement cannot be carried out accurately by a manometer for dynamic fluid motion in a pipe.
a) True
b) False
Correct Option: (a)
Explanation: A manometer cannot be used because the variation in pressure is frequent and more in magnitude for fluid moving with variable velocity.
Practice Questions
1) What is a barometer?
2) What is pressure?
3) Define viscosity.
4) How does a barometer work?
5) Who invented the barometer?
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