Air bubble of 0.4 mm diameter is situated just below the surface of water. The gauge pressure inside bubble is X mm of Hg. Find the value of X till two decimal places.
Take surface tension of water = 0.07N/m and `g=10m//s^(2)`.

Answer

`05.15`

Explanation

Excess pressure inside air bubble,
`P_(i) -P_(0)=(2T)/(R ) =(2xx0.07)/(2xx10^(-4)) =700 N//m^(2)`
Let required gauge pressure be equal to h
`:.hpg=P_(i) -P_(0)`
`:.h=(700)/(13.6 xx 10^(3) xx 10) =(70)/(13.6) xx 10^(-3) m =5.147xx 10^(-3)m`
`:.h=5.15 xx 10^(-3)m`
......(Rounding off to 2 decimal places)