Atmospheric Pressure

A piston of mass M = 3kg and radius R = 4cm has a hole into which a thin pipe of radius r = 1cm is inserted. The piston can enter a cylinder tightly and without friction, and initially it is at the bottom of the cylinder. 750gm of water is now poured into the pipe so that the piston & pipe are lifted up as shown. Find the height H of water in the cylinder h of water in the pipe

The height of the mercury column in a simple barometer is h. As the tube is inclined with the vertical at an angle $\alpha$, the length of the mercury column along the length of the tube will become 

Water of density $\rho$ in a clean aquarium forms a meniscus, as illustrated in the figure. Calculate the difference in height $h$ between the centre and the edge of the meniscus. The surface tension of water is $\gamma$.

A mercury barometer has a cylindrical capillary tube of radius $\mathrm{r}=\sqrt{2} \mathrm{mm}$ inverted vertically on the mercury in the trough. Atmospheric pressure is $76 \mathrm{cm}$ of mercury but the level of mercury in the capillary is $75 \mathrm{cm}$. The portion of the tube without mercury is $10 \mathrm{cm}$ in length. Considering that this region is occupied by ideal gasses, the number of moles of the ideal gas will be : (Given: Temperature $=37°\mathrm{C}$)

Where will the vacuum be formed in case of a faulty barometer?

In the event of a faulty barometer, vacuum does not form above the mercury level.

When a barometer is faulty, the pressure in it increases. Why?

When a barometer is faulty, the air is unable to escape completely. 

What happens when a barometer is faulty?

Altimeter is an equipment used to measure the atmospheric pressure.

What do you mean by altimeter?

Select the uses of barometer:

What are the uses of barometers?

A barometer is used to measure the energy applied by atmosphere.

Which of the following is better to use?

It is better to use an aneroid barometer than a simple barometer.

How does an aneroid barometer work? What are its advantages over mercury barometer?

How does the barometric height depend upon the change in altitude?

The vertical height of mercury in the tube must remain constant regardless of the cross-sectional area or shape of the tube as long as the atmospheric pressure remains constant.

Which of the following factors affect the barometric height?