When liquid medicine `rho` is to be put in the eye, it is done with the help of a dropper. As the
Channel: Doubtnut
Date: 2020-01-26

When liquid medicine `rho` is to be put in the eye, it is done with the help of a dropper. As the bulb on the top of the dropper is pressed, a drop froms at the opening of the dropper. We wish to estimate the size of the drop. We first assume that the drop formed at the opening is osperical becaus ethat requires a minimum increase in its surface energy. To datermine the size., we calculate the net vertical force due to the surface tension `T` when the radius of the drop is `R`. When this force become smaller than the wight of the drop, the drop gets detached from the droppr. Four point charges, each of `+q`, are rigidly fixed at the four corners of a squre planer soap film of side `\'a\'` the surface tenson of the soap film is `gamma`. The susteam of charges and planer film are in equilibrium, and `a = k[(q^(2))/(gamma)]^(1//N)`, where `\'k\'` is a constant. Then `N` is