The atmospheric pressure at a surface depends on the height of the air column above it.

An open-ended U-tube of uniform cross-sectional area contains water (density ${10}^3 \mathrm{kg} {\mathrm{m}}^{-3}$ ). Initially the water level stands at $0.29 \mathrm{m}$ from the bottom in each arm. Kerosene oil (a water-immiscible liquid) of density $800 \mathrm{kg} {\mathrm{m}}^{-3}$ is added to the left arm until its length is $0.1 \mathrm{m}$, as shown in the schematic figure below. The ratio $\left(\frac{h_1}{h_2}\right)$ of the heights of the liquid in the two arms is

Calculate the difference $\left(h\right)$ in water levels in two communicating capillary tubes of radius $1 \mathrm{mm}$ and $1.5 \mathrm{mm}$.

(Surface tension of water is $0.07\mathrm{ }\mathrm{N} {\mathrm{m}}^{-1}$)

A vertical tube of length $100 \mathrm{cm}$ contains a mercury pallet of length $5 \mathrm{cm}$ as shown in the figure. The length of the tube above mercury pallet if the tube is inverted is nearly: (atmospheric pressure = $75 \mathrm{cm}$ of Hg)