An oil droplet of 0.01 mm diameter floats in equilibrium between two horizontal plates the distance between which is 25 mm. What is the charge of the droplet, if the equilibrium corresponds to a voltage of `3.6 xx 10^(4)V` across the plates?

Explanation

A force of gravity directed downwards and equal to `mig=4//6pi D^(8)rhog` acts on the droplet. It is countorboloncod by on blootrio force `F=qE=q varphi//d` (Fig. 24.4). The charge of the droplet is found from the balance of forces.