An isolated and charged spherical soap bubble has a radius ‘ r ‘ and the pressure inside is atmospheric. If ‘ T ‘ is the surface tension of soap solution, then charge on drop is:

Options

A. `2sqrt((2r T)/(epsilon_(0)))`
B. `8 pi rsqrt(2r T epsilon_(0))`
C. `8 pi r sqrt(r T epsilon_(0))`
D. `8 pi r sqrt((2rT)/(epsilon_(0)))`

Answer

B

Explanation

Inside pressure nust be `(4T)/(r)` greater then outside pressure in bubble. This excess pressure is provided by charge on bubble.

`(4T)/(r) = (sigma^(2))/(2 epsilon_(0))`
`(4T)/(r)=(Q^(2))/(16 pi^(2)r^(4)xx2 epsilon_())....[sigma =(Q)/(4 pir^(2))]`
`Q =8 pi r sqrt(2r T epsilon_(0))`.